Exit while loop by user hitting ENTER key
You need to find out what the variable User would look like when you just press Enter. I won't give you the full answer, but a tip: Fire an interpreter and try it out. It's not that hard ;) Notice that print's sep is '\n' by default (was that too much :o)
Unable to connect to SQL Server instance remotely
I recently upgraded from SQL 2008 R2 to SQL 2012 and had a similar issue. The problem was the firewall, but more specifically the firewall rule for SQL SERVER. The custom rule was pointed to the prior version of SQL Server. Try this, open Windows Firewall>Advanced setting. Find the SQL Server Rule (it may have a custom name). Right-Click and go to properties, then Programs and Services Tab. If Programs-This program is selected, you should browse for the proper version of sqlserver.exe.
How do I check form validity with angularjs?
When you put <form>
tag inside you ngApp, AngularJS automatically adds form controller (actually there is a directive, called form
that add nessesary behaviour). The value of the name attribute will be bound in your scope; so something like <form name="yourformname">...</form>
will satisfy:
A form is an instance of FormController. The form instance can optionally be published into the scope using the name attribute.
So to check form validity, you can check value of $scope.yourformname.$valid
property of scope.
More information you can get at Developer's Guide section about forms.
Alternative for PHP_excel
For Writing Excel
- PEAR's PHP_Excel_Writer (xls only)
- php_writeexcel from Bettina
Attack (xls only)
- XLS File Generator commercial and xls only
- Excel Writer for PHP from Sourceforge (spreadsheetML only)
- Ilia Alshanetsky's Excel extension now on github (xls and xlsx, and requires commercial libXL component)
- PHP's COM extension (requires a COM enabled spreadsheet program such as MS Excel or OpenOffice Calc running on the server)
- The Open Office alternative to COM (PUNO) (requires Open Office installed on the server with Java support enabled)
- PHP-Export-Data by Eli Dickinson (Writes SpreadsheetML - the Excel 2003 XML format, and CSV)
- Oliver Schwarz's php-excel (SpreadsheetML)
- Oliver Schwarz's original version of php-excel (SpreadsheetML)
- excel_xml (SpreadsheetML, despite its name)... link reported as broken
- The tiny-but-strong (tbs) project includes the OpenTBS tool for creating OfficeOpenXML documents (OpenDocument and OfficeOpenXML formats)
- SimpleExcel Claims to read and write Microsoft Excel XML / CSV / TSV / HTML / JSON / etc formats
- KoolGrid xls spreadsheets only, but also doc and pdf
- PHP_XLSXWriter OfficeOpenXML
- PHP_XLSXWriter_plus OfficeOpenXML, fork of PHP_XLSXWriter
- php_writeexcel xls only (looks like it's based on PEAR SEW)
- spout OfficeOpenXML (xlsx) and CSV
- Slamdunk/php-excel (xls only) looks like an updated version of the old PEAR Spreadsheet Writer
For Reading Excel
A new C++ Excel extension for PHP, though you'll need to build it yourself, and the docs are pretty sparse when it comes to trying to find out what functionality (I can't even find out from the site what formats it supports, or whether it reads or writes or both.... I'm guessing both) it offers is phpexcellib from SIMITGROUP.
All claim to be faster than PHPExcel from codeplex or from github, but (with the exception of COM, PUNO Ilia's wrapper around libXl and spout) they don't offer both reading and writing, or both xls and xlsx; may no longer be supported; and (while I haven't tested Ilia's extension) only COM and PUNO offers the same degree of control over the created workbook.
Nullable property to entity field, Entity Framework through Code First
Just omit the [Required] attribute from the string somefield
property. This will make it create a NULL
able column in the db.
To make int types allow NULLs in the database, they must be declared as nullable ints in the model:
// an int can never be null, so it will be created as NOT NULL in db
public int someintfield { get; set; }
// to have a nullable int, you need to declare it as an int?
// or as a System.Nullable<int>
public int? somenullableintfield { get; set; }
public System.Nullable<int> someothernullableintfield { get; set; }
Dynamically change bootstrap progress bar value when checkboxes checked
Try this maybe :
Bootply : http://www.bootply.com/106527
Js :
$('input').on('click', function(){
var valeur = 0;
$('input:checked').each(function(){
if ( $(this).attr('value') > valeur )
{
valeur = $(this).attr('value');
}
});
$('.progress-bar').css('width', valeur+'%').attr('aria-valuenow', valeur);
});
HTML :
<div class="progress progress-striped active">
<div class="progress-bar" role="progressbar" aria-valuenow="0" aria-valuemin="0" aria-valuemax="100">
</div>
</div>
<div class="row tasks">
<div class="col-md-6">
<p><span>Identify your campaign audience.</span>Who are we talking to here? Understand your buyer persona before launching into a campaign, so you can target them correctly.</p>
</div>
<div class="col-md-2">
<label>2014-01-29</label>
</div>
<div class="col-md-2">
<input name="progress" class="progress" type="checkbox" value="10">
</div>
<div class="col-md-2">
<input name="done" class="done" type="checkbox" value="20">
</div>
</div><!-- tasks -->
<div class="row tasks">
<div class="col-md-6">
<p><span>Set your goals + benchmarks</span>Having SMART goals can help you be
sure that you’ll have tangible results to share with the world (or your
boss) at the end of your campaign.</p>
</div>
<div class="col-md-2">
<label>2014-01-25</label>
</div>
<div class="col-md-2">
<input name="progress" class="progress" type="checkbox" value="30">
</div>
<div class="col-md-2">
<input name="done" class="done" type="checkbox" value="40">
</div>
</div><!-- tasks -->
Css
.tasks{
background-color: #F6F8F8;
padding: 10px;
border-radius: 5px;
margin-top: 10px;
}
.tasks span{
font-weight: bold;
}
.tasks input{
display: block;
margin: 0 auto;
margin-top: 10px;
}
.tasks a{
color: #000;
text-decoration: none;
border:none;
}
.tasks a:hover{
border-bottom: dashed 1px #0088cc;
}
.tasks label{
display: block;
text-align: center;
}
_x000D_
_x000D_
$(function(){_x000D_
$('input').on('click', function(){_x000D_
var valeur = 0;_x000D_
$('input:checked').each(function(){_x000D_
if ( $(this).attr('value') > valeur )_x000D_
{_x000D_
valeur = $(this).attr('value');_x000D_
}_x000D_
});_x000D_
$('.progress-bar').css('width', valeur+'%').attr('aria-valuenow', valeur); _x000D_
});_x000D_
_x000D_
});
_x000D_
.tasks{_x000D_
background-color: #F6F8F8;_x000D_
padding: 10px;_x000D_
border-radius: 5px;_x000D_
margin-top: 10px;_x000D_
}_x000D_
.tasks span{_x000D_
font-weight: bold;_x000D_
}_x000D_
.tasks input{_x000D_
display: block;_x000D_
margin: 0 auto;_x000D_
margin-top: 10px;_x000D_
}_x000D_
.tasks a{_x000D_
color: #000;_x000D_
text-decoration: none;_x000D_
border:none;_x000D_
}_x000D_
.tasks a:hover{_x000D_
border-bottom: dashed 1px #0088cc;_x000D_
}_x000D_
.tasks label{_x000D_
display: block;_x000D_
text-align: center;_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>_x000D_
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>_x000D_
_x000D_
<div class="progress progress-striped active">_x000D_
<div class="progress-bar" role="progressbar" aria-valuenow="0" aria-valuemin="0" aria-valuemax="100">_x000D_
</div>_x000D_
</div>_x000D_
<div class="row tasks">_x000D_
<div class="col-md-6">_x000D_
<p><span>Identify your campaign audience.</span>Who are we talking to here? Understand your buyer persona before launching into a campaign, so you can target them correctly.</p>_x000D_
</div>_x000D_
<div class="col-md-2">_x000D_
<label>2014-01-29</label>_x000D_
</div>_x000D_
<div class="col-md-2">_x000D_
<input name="progress" class="progress" type="checkbox" value="10">_x000D_
</div>_x000D_
<div class="col-md-2">_x000D_
<input name="done" class="done" type="checkbox" value="20">_x000D_
</div>_x000D_
</div><!-- tasks -->_x000D_
_x000D_
<div class="row tasks">_x000D_
<div class="col-md-6">_x000D_
<p><span>Set your goals + benchmarks</span>Having SMART goals can help you be_x000D_
sure that you’ll have tangible results to share with the world (or your_x000D_
boss) at the end of your campaign.</p>_x000D_
</div>_x000D_
<div class="col-md-2">_x000D_
<label>2014-01-25</label>_x000D_
</div>_x000D_
<div class="col-md-2">_x000D_
<input name="progress" class="progress" type="checkbox" value="30">_x000D_
</div>_x000D_
<div class="col-md-2">_x000D_
<input name="done" class="done" type="checkbox" value="40">_x000D_
</div>_x000D_
</div><!-- tasks -->
_x000D_
_x000D_
_x000D_
How can I call the 'base implementation' of an overridden virtual method?
It's impossible if the method is declared in the derived class as overrides
. to do that, the method in the derived class should be declared as new
:
public class Base {
public virtual string X() {
return "Base";
}
}
public class Derived1 : Base
{
public new string X()
{
return "Derived 1";
}
}
public class Derived2 : Base
{
public override string X() {
return "Derived 2";
}
}
Derived1 a = new Derived1();
Base b = new Derived1();
Base c = new Derived2();
a.X(); // returns Derived 1
b.X(); // returns Base
c.X(); // returns Derived 2
See fiddle here
System.Timers.Timer vs System.Threading.Timer
One important difference not mentioned above which might catch you out is that System.Timers.Timer
silently swallows exceptions, whereas System.Threading.Timer
doesn't.
For example:
var timer = new System.Timers.Timer { AutoReset = false };
timer.Elapsed += (sender, args) =>
{
var z = 0;
var i = 1 / z;
};
timer.Start();
vs
var timer = new System.Threading.Timer(x =>
{
var z = 0;
var i = 1 / z;
}, null, 0, Timeout.Infinite);
Accessing an SQLite Database in Swift
Sometimes, a Swift version of the "SQLite in 5 minutes or less" approach shown on sqlite.org is sufficient.
The "5 minutes or less" approach uses sqlite3_exec()
which is a convenience wrapper for sqlite3_prepare()
, sqlite3_step()
, sqlite3_column()
, and sqlite3_finalize()
.
Swift 2.2 can directly support the sqlite3_exec()
callback
function pointer as either a global, non-instance procedure func
or a non-capturing literal closure {}
.
Readable typealias
typealias sqlite3 = COpaquePointer
typealias CCharHandle = UnsafeMutablePointer<UnsafeMutablePointer<CChar>>
typealias CCharPointer = UnsafeMutablePointer<CChar>
typealias CVoidPointer = UnsafeMutablePointer<Void>
Callback Approach
func callback(
resultVoidPointer: CVoidPointer, // void *NotUsed
columnCount: CInt, // int argc
values: CCharHandle, // char **argv
columns: CCharHandle // char **azColName
) -> CInt {
for i in 0 ..< Int(columnCount) {
guard let value = String.fromCString(values[i])
else { continue }
guard let column = String.fromCString(columns[i])
else { continue }
print("\(column) = \(value)")
}
return 0 // status ok
}
func sqlQueryCallbackBasic(argc: Int, argv: [String]) -> Int {
var db: sqlite3 = nil
var zErrMsg:CCharPointer = nil
var rc: Int32 = 0 // result code
if argc != 3 {
print(String(format: "ERROR: Usage: %s DATABASE SQL-STATEMENT", argv[0]))
return 1
}
rc = sqlite3_open(argv[1], &db)
if rc != 0 {
print("ERROR: sqlite3_open " + String.fromCString(sqlite3_errmsg(db))! ?? "" )
sqlite3_close(db)
return 1
}
rc = sqlite3_exec(db, argv[2], callback, nil, &zErrMsg)
if rc != SQLITE_OK {
print("ERROR: sqlite3_exec " + String.fromCString(zErrMsg)! ?? "")
sqlite3_free(zErrMsg)
}
sqlite3_close(db)
return 0
}
Closure Approach
func sqlQueryClosureBasic(argc argc: Int, argv: [String]) -> Int {
var db: sqlite3 = nil
var zErrMsg:CCharPointer = nil
var rc: Int32 = 0
if argc != 3 {
print(String(format: "ERROR: Usage: %s DATABASE SQL-STATEMENT", argv[0]))
return 1
}
rc = sqlite3_open(argv[1], &db)
if rc != 0 {
print("ERROR: sqlite3_open " + String.fromCString(sqlite3_errmsg(db))! ?? "" )
sqlite3_close(db)
return 1
}
rc = sqlite3_exec(
db, // database
argv[2], // statement
{ // callback: non-capturing closure
resultVoidPointer, columnCount, values, columns in
for i in 0 ..< Int(columnCount) {
guard let value = String.fromCString(values[i])
else { continue }
guard let column = String.fromCString(columns[i])
else { continue }
print("\(column) = \(value)")
}
return 0
},
nil,
&zErrMsg
)
if rc != SQLITE_OK {
let errorMsg = String.fromCString(zErrMsg)! ?? ""
print("ERROR: sqlite3_exec \(errorMsg)")
sqlite3_free(zErrMsg)
}
sqlite3_close(db)
return 0
}
To prepare an Xcode project to call a C library such as SQLite, one needs to (1) add a Bridging-Header.h file reference C headers like #import "sqlite3.h"
, (2) add Bridging-Header.h to Objective-C Bridging Header in project settings, and (3) add libsqlite3.tbd
to Link Binary With Library target settings.
The sqlite.org's "SQLite in 5 minutes or less" example is implemented in a Swift Xcode7 project here.
Confused about UPDLOCK, HOLDLOCK
Why would UPDLOCK block selects? The Lock Compatibility Matrix clearly shows N
for the S/U and U/S contention, as in No Conflict.
As for the HOLDLOCK hint the documentation states:
HOLDLOCK: Is equivalent to SERIALIZABLE. For more information, see SERIALIZABLE
later in this topic.
...
SERIALIZABLE: ... The scan is performed with the same semantics as a transaction running at the SERIALIZABLE isolation level...
and the Transaction Isolation Level topic explains what SERIALIZABLE means:
No other transactions can modify data that has been read by the
current transaction until the current transaction completes.
Other transactions cannot insert new rows with key values that would
fall in the range of keys read by any statements in the current
transaction until the current transaction completes.
Therefore the behavior you see is perfectly explained by the product documentation:
- UPDLOCK does not block concurrent SELECT nor INSERT, but blocks any UPDATE or DELETE of the rows selected by T1
- HOLDLOCK means SERALIZABLE and therefore allows SELECTS, but blocks UPDATE and DELETES of the rows selected by T1, as well as any INSERT in the range selected by T1 (which is the entire table, therefore any insert).
- (UPDLOCK, HOLDLOCK): your experiment does not show what would block in addition to the case above, namely another transaction with UPDLOCK in T2:
SELECT * FROM dbo.Test WITH (UPDLOCK) WHERE ...
- TABLOCKX no need for explanations
The real question is what are you trying to achieve? Playing with lock hints w/o an absolute complete 110% understanding of the locking semantics is begging for trouble...
After OP edit:
I would like to select rows from a table and prevent the data in that
table from being modified while I am processing it.
The you should use one of the higher transaction isolation levels. REPEATABLE READ will prevent the data you read from being modified. SERIALIZABLE will prevent the data you read from being modified and new data from being inserted. Using transaction isolation levels is the right approach, as opposed to using query hints. Kendra Little has a nice poster exlaining the isolation levels.
Default value to a parameter while passing by reference in C++
You can do it for a const reference, but not for a non-const one. This is because C++ does not allow a temporary (the default value in this case) to be bound to non-const reference.
One way round this would be to use an actual instance as the default:
static int AVAL = 1;
void f( int & x = AVAL ) {
// stuff
}
int main() {
f(); // equivalent to f(AVAL);
}
but this is of very limited practical use.
How to connect html pages to mysql database?
HTML are markup languages, basically they are set of tags like <html>
, <body>
, which is used to present a website using css, and javascript as a whole. All these, happen in the clients system or the user you will be browsing the website.
Now, Connecting to a database, happens on whole another level. It happens on server, which is where the website is hosted.
So, in order to connect to the database and perform various data related actions, you have to use server-side scripts, like php, jsp, asp.net etc.
Now, lets see a snippet of connection using MYSQLi Extension of PHP
$db = mysqli_connect('hostname','username','password','databasename');
This single line code, is enough to get you started, you can mix such code, combined with HTML tags to create a HTML page, which is show data based pages. For example:
<?php
$db = mysqli_connect('hostname','username','password','databasename');
?>
<html>
<body>
<?php
$query = "SELECT * FROM `mytable`;";
$result = mysqli_query($db, $query);
while($row = mysqli_fetch_assoc($result)) {
// Display your datas on the page
}
?>
</body>
</html>
In order to insert new data into the database, you can use phpMyAdmin
or write a INSERT
query and execute them.
Hamcrest compare collections
List<Long> actual = Arrays.asList(1L, 2L);
List<Long> expected = Arrays.asList(2L, 1L);
assertThat(actual, containsInAnyOrder(expected.toArray()));
Shorter version of @Joe's answer without redundant parameters.
Show/hide 'div' using JavaScript
Just Simple Function Need To implement Show/hide 'div' using JavaScript
<a id="morelink" class="link-more" style="font-weight: bold; display: block;" onclick="this.style.display='none'; document.getElementById('states').style.display='block'; return false;">READ MORE</a>
<div id="states" style="display: block; line-height: 1.6em;">
text here text here text here text here text here text here text here text here text here text here text here text here text here text here text here text here text here text here text here text here
<a class="link-less" style="font-weight: bold;" onclick="document.getElementById('morelink').style.display='inline-block'; document.getElementById('states').style.display='none'; return false;">LESS INFORMATION</a>
</div>
Convert a Map<String, String> to a POJO
The answers provided so far using Jackson are so good, but still you could have a util function to help you convert different POJO
s as follows:
public static <T> T convert(Map<String, Object> aMap, Class<T> t) {
try {
return objectMapper
.convertValue(aMap, objectMapper.getTypeFactory().constructType(t));
} catch (Exception e) {
log.error("converting failed! aMap: {}, class: {}", getJsonString(aMap), t.getClass().getSimpleName(), e);
}
return null;
}
How do you sign a Certificate Signing Request with your Certification Authority?
1. Using the x509 module
openssl x509 ...
...
2 Using the ca module
openssl ca ...
...
You are missing the prelude to those commands.
This is a two-step process. First you set up your CA, and then you sign an end entity certificate (a.k.a server or user). Both of the two commands elide the two steps into one. And both assume you have a an OpenSSL configuration file already setup for both CAs and Server (end entity) certificates.
First, create a basic configuration file:
$ touch openssl-ca.cnf
Then, add the following to it:
HOME = .
RANDFILE = $ENV::HOME/.rnd
####################################################################
[ ca ]
default_ca = CA_default # The default ca section
[ CA_default ]
default_days = 1000 # How long to certify for
default_crl_days = 30 # How long before next CRL
default_md = sha256 # Use public key default MD
preserve = no # Keep passed DN ordering
x509_extensions = ca_extensions # The extensions to add to the cert
email_in_dn = no # Don't concat the email in the DN
copy_extensions = copy # Required to copy SANs from CSR to cert
####################################################################
[ req ]
default_bits = 4096
default_keyfile = cakey.pem
distinguished_name = ca_distinguished_name
x509_extensions = ca_extensions
string_mask = utf8only
####################################################################
[ ca_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = US
stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = Maryland
localityName = Locality Name (eg, city)
localityName_default = Baltimore
organizationName = Organization Name (eg, company)
organizationName_default = Test CA, Limited
organizationalUnitName = Organizational Unit (eg, division)
organizationalUnitName_default = Server Research Department
commonName = Common Name (e.g. server FQDN or YOUR name)
commonName_default = Test CA
emailAddress = Email Address
emailAddress_default = [email protected]
####################################################################
[ ca_extensions ]
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always, issuer
basicConstraints = critical, CA:true
keyUsage = keyCertSign, cRLSign
The fields above are taken from a more complex openssl.cnf
(you can find it in /usr/lib/openssl.cnf
), but I think they are the essentials for creating the CA certificate and private key.
Tweak the fields above to suit your taste. The defaults save you the time from entering the same information while experimenting with configuration file and command options.
I omitted the CRL-relevant stuff, but your CA operations should have them. See openssl.cnf
and the related crl_ext
section.
Then, execute the following. The -nodes
omits the password or passphrase so you can examine the certificate. It's a really bad idea to omit the password or passphrase.
$ openssl req -x509 -config openssl-ca.cnf -newkey rsa:4096 -sha256 -nodes -out cacert.pem -outform PEM
After the command executes, cacert.pem
will be your certificate for CA operations, and cakey.pem
will be the private key. Recall the private key does not have a password or passphrase.
You can dump the certificate with the following.
$ openssl x509 -in cacert.pem -text -noout
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 11485830970703032316 (0x9f65de69ceef2ffc)
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, ST=MD, L=Baltimore, CN=Test CA/[email protected]
Validity
Not Before: Jan 24 14:24:11 2014 GMT
Not After : Feb 23 14:24:11 2014 GMT
Subject: C=US, ST=MD, L=Baltimore, CN=Test CA/[email protected]
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (4096 bit)
Modulus:
00:b1:7f:29:be:78:02:b8:56:54:2d:2c:ec:ff:6d:
...
39:f9:1e:52:cb:8e:bf:8b:9e:a6:93:e1:22:09:8b:
59:05:9f
Exponent: 65537 (0x10001)
X509v3 extensions:
X509v3 Subject Key Identifier:
4A:9A:F3:10:9E:D7:CF:54:79:DE:46:75:7A:B0:D0:C1:0F:CF:C1:8A
X509v3 Authority Key Identifier:
keyid:4A:9A:F3:10:9E:D7:CF:54:79:DE:46:75:7A:B0:D0:C1:0F:CF:C1:8A
X509v3 Basic Constraints: critical
CA:TRUE
X509v3 Key Usage:
Certificate Sign, CRL Sign
Signature Algorithm: sha256WithRSAEncryption
4a:6f:1f:ac:fd:fb:1e:a4:6d:08:eb:f5:af:f6:1e:48:a5:c7:
...
cd:c6:ac:30:f9:15:83:41:c1:d1:20:fa:85:e7:4f:35:8f:b5:
38:ff:fd:55:68:2c:3e:37
And test its purpose with the following (don't worry about the Any Purpose: Yes
; see "critical,CA:FALSE" but "Any Purpose CA : Yes").
$ openssl x509 -purpose -in cacert.pem -inform PEM
Certificate purposes:
SSL client : No
SSL client CA : Yes
SSL server : No
SSL server CA : Yes
Netscape SSL server : No
Netscape SSL server CA : Yes
S/MIME signing : No
S/MIME signing CA : Yes
S/MIME encryption : No
S/MIME encryption CA : Yes
CRL signing : Yes
CRL signing CA : Yes
Any Purpose : Yes
Any Purpose CA : Yes
OCSP helper : Yes
OCSP helper CA : Yes
Time Stamp signing : No
Time Stamp signing CA : Yes
-----BEGIN CERTIFICATE-----
MIIFpTCCA42gAwIBAgIJAJ9l3mnO7y/8MA0GCSqGSIb3DQEBCwUAMGExCzAJBgNV
...
aQUtFrV4hpmJUaQZ7ySr/RjCb4KYkQpTkOtKJOU1Ic3GrDD5FYNBwdEg+oXnTzWP
tTj//VVoLD43
-----END CERTIFICATE-----
For part two, I'm going to create another configuration file that's easily digestible. First, touch
the openssl-server.cnf
(you can make one of these for user certificates also).
$ touch openssl-server.cnf
Then open it, and add the following.
HOME = .
RANDFILE = $ENV::HOME/.rnd
####################################################################
[ req ]
default_bits = 2048
default_keyfile = serverkey.pem
distinguished_name = server_distinguished_name
req_extensions = server_req_extensions
string_mask = utf8only
####################################################################
[ server_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = US
stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = MD
localityName = Locality Name (eg, city)
localityName_default = Baltimore
organizationName = Organization Name (eg, company)
organizationName_default = Test Server, Limited
commonName = Common Name (e.g. server FQDN or YOUR name)
commonName_default = Test Server
emailAddress = Email Address
emailAddress_default = [email protected]
####################################################################
[ server_req_extensions ]
subjectKeyIdentifier = hash
basicConstraints = CA:FALSE
keyUsage = digitalSignature, keyEncipherment
subjectAltName = @alternate_names
nsComment = "OpenSSL Generated Certificate"
####################################################################
[ alternate_names ]
DNS.1 = example.com
DNS.2 = www.example.com
DNS.3 = mail.example.com
DNS.4 = ftp.example.com
If you are developing and need to use your workstation as a server, then you may need to do the following for Chrome. Otherwise Chrome may complain a Common Name is invalid (ERR_CERT_COMMON_NAME_INVALID
). I'm not sure what the relationship is between an IP address in the SAN and a CN in this instance.
# IPv4 localhost
IP.1 = 127.0.0.1
# IPv6 localhost
IP.2 = ::1
Then, create the server certificate request. Be sure to omit -x509
*. Adding -x509
will create a certificate, and not a request.
$ openssl req -config openssl-server.cnf -newkey rsa:2048 -sha256 -nodes -out servercert.csr -outform PEM
After this command executes, you will have a request in servercert.csr
and a private key in serverkey.pem
.
And you can inspect it again.
$ openssl req -text -noout -verify -in servercert.csr
Certificate:
verify OK
Certificate Request:
Version: 0 (0x0)
Subject: C=US, ST=MD, L=Baltimore, CN=Test Server/[email protected]
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
Modulus:
00:ce:3d:58:7f:a0:59:92:aa:7c:a0:82:dc:c9:6d:
...
f9:5e:0c:ba:84:eb:27:0d:d9:e7:22:5d:fe:e5:51:
86:e1
Exponent: 65537 (0x10001)
Attributes:
Requested Extensions:
X509v3 Subject Key Identifier:
1F:09:EF:79:9A:73:36:C1:80:52:60:2D:03:53:C7:B6:BD:63:3B:61
X509v3 Basic Constraints:
CA:FALSE
X509v3 Key Usage:
Digital Signature, Key Encipherment
X509v3 Subject Alternative Name:
DNS:example.com, DNS:www.example.com, DNS:mail.example.com, DNS:ftp.example.com
Netscape Comment:
OpenSSL Generated Certificate
Signature Algorithm: sha256WithRSAEncryption
6d:e8:d3:85:b3:88:d4:1a:80:9e:67:0d:37:46:db:4d:9a:81:
...
76:6a:22:0a:41:45:1f:e2:d6:e4:8f:a1:ca:de:e5:69:98:88:
a9:63:d0:a7
Next, you have to sign it with your CA.
You are almost ready to sign the server's certificate by your CA. The CA's openssl-ca.cnf
needs two more sections before issuing the command.
First, open openssl-ca.cnf
and add the following two sections.
####################################################################
[ signing_policy ]
countryName = optional
stateOrProvinceName = optional
localityName = optional
organizationName = optional
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
####################################################################
[ signing_req ]
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
basicConstraints = CA:FALSE
keyUsage = digitalSignature, keyEncipherment
Second, add the following to the [ CA_default ]
section of openssl-ca.cnf
. I left them out earlier, because they can complicate things (they were unused at the time). Now you'll see how they are used, so hopefully they will make sense.
base_dir = .
certificate = $base_dir/cacert.pem # The CA certifcate
private_key = $base_dir/cakey.pem # The CA private key
new_certs_dir = $base_dir # Location for new certs after signing
database = $base_dir/index.txt # Database index file
serial = $base_dir/serial.txt # The current serial number
unique_subject = no # Set to 'no' to allow creation of
# several certificates with same subject.
Third, touch index.txt
and serial.txt
:
$ touch index.txt
$ echo '01' > serial.txt
Then, perform the following:
$ openssl ca -config openssl-ca.cnf -policy signing_policy -extensions signing_req -out servercert.pem -infiles servercert.csr
You should see similar to the following:
Using configuration from openssl-ca.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName :PRINTABLE:'US'
stateOrProvinceName :ASN.1 12:'MD'
localityName :ASN.1 12:'Baltimore'
commonName :ASN.1 12:'Test CA'
emailAddress :IA5STRING:'[email protected]'
Certificate is to be certified until Oct 20 16:12:39 2016 GMT (1000 days)
Sign the certificate? [y/n]:Y
1 out of 1 certificate requests certified, commit? [y/n]Y
Write out database with 1 new entries
Data Base Updated
After the command executes, you will have a freshly minted server certificate in servercert.pem
. The private key was created earlier and is available in serverkey.pem
.
Finally, you can inspect your freshly minted certificate with the following:
$ openssl x509 -in servercert.pem -text -noout
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 9 (0x9)
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, ST=MD, L=Baltimore, CN=Test CA/[email protected]
Validity
Not Before: Jan 24 19:07:36 2014 GMT
Not After : Oct 20 19:07:36 2016 GMT
Subject: C=US, ST=MD, L=Baltimore, CN=Test Server
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
Modulus:
00:ce:3d:58:7f:a0:59:92:aa:7c:a0:82:dc:c9:6d:
...
f9:5e:0c:ba:84:eb:27:0d:d9:e7:22:5d:fe:e5:51:
86:e1
Exponent: 65537 (0x10001)
X509v3 extensions:
X509v3 Subject Key Identifier:
1F:09:EF:79:9A:73:36:C1:80:52:60:2D:03:53:C7:B6:BD:63:3B:61
X509v3 Authority Key Identifier:
keyid:42:15:F2:CA:9C:B1:BB:F5:4C:2C:66:27:DA:6D:2E:5F:BA:0F:C5:9E
X509v3 Basic Constraints:
CA:FALSE
X509v3 Key Usage:
Digital Signature, Key Encipherment
X509v3 Subject Alternative Name:
DNS:example.com, DNS:www.example.com, DNS:mail.example.com, DNS:ftp.example.com
Netscape Comment:
OpenSSL Generated Certificate
Signature Algorithm: sha256WithRSAEncryption
b1:40:f6:34:f4:38:c8:57:d4:b6:08:f7:e2:71:12:6b:0e:4a:
...
45:71:06:a9:86:b6:0f:6d:8d:e1:c5:97:8d:fd:59:43:e9:3c:
56:a5:eb:c8:7e:9f:6b:7a
Earlier, you added the following to CA_default
: copy_extensions = copy
. This copies extension provided by the person making the request.
If you omit copy_extensions = copy
, then your server certificate will lack the Subject Alternate Names (SANs) like www.example.com
and mail.example.com
.
If you use copy_extensions = copy
, but don't look over the request, then the requester might be able to trick you into signing something like a subordinate root (rather than a server or user certificate). Which means he/she will be able to mint certificates that chain back to your trusted root. Be sure to verify the request with openssl req -verify
before signing.
If you omit unique_subject
or set it to yes
, then you will only be allowed to create one certificate under the subject's distinguished name.
unique_subject = yes # Set to 'no' to allow creation of
# several ctificates with same subject.
Trying to create a second certificate while experimenting will result in the following when signing your server's certificate with the CA's private key:
Sign the certificate? [y/n]:Y
failed to update database
TXT_DB error number 2
So unique_subject = no
is perfect for testing.
If you want to ensure the Organizational Name is consistent between self-signed CAs, Subordinate CA and End-Entity certificates, then add the following to your CA configuration files:
[ policy_match ]
organizationName = match
If you want to allow the Organizational Name to change, then use:
[ policy_match ]
organizationName = supplied
There are other rules concerning the handling of DNS names in X.509/PKIX certificates. Refer to these documents for the rules:
RFC 6797 and RFC 7469 are listed, because they are more restrictive than the other RFCs and CA/B documents. RFC's 6797 and 7469 do not allow an IP address, either.
getting " (1) no such column: _id10 " error
I think you missed a equal sign at:
Cursor c = ourDatabase.query(DATABASE_TABLE, column, KEY_ROWID + "" + l, null, null, null, null);
Change to:
Cursor c = ourDatabase.query(DATABASE_TABLE, column, KEY_ROWID + " = " + l, null, null, null, null);
programming a servo thru a barometer
You could define a mapping of air pressure to servo angle, for example:
def calc_angle(pressure, min_p=1000, max_p=1200): return 360 * ((pressure - min_p) / float(max_p - min_p)) angle = calc_angle(pressure)
This will linearly convert pressure
values between min_p
and max_p
to angles between 0 and 360 (you could include min_a
and max_a
to constrain the angle, too).
To pick a data structure, I wouldn't use a list but you could look up values in a dictionary:
d = {1000:0, 1001: 1.8, ...} angle = d[pressure]
but this would be rather time-consuming to type out!
Android turn On/Off WiFi HotSpot programmatically
Warning This method will not work beyond 5.0, it was a quite dated entry.
Use the class below to change/check the Wifi hotspot
setting:
import android.content.*;
import android.net.wifi.*;
import java.lang.reflect.*;
public class ApManager {
//check whether wifi hotspot on or off
public static boolean isApOn(Context context) {
WifiManager wifimanager = (WifiManager) context.getSystemService(context.WIFI_SERVICE);
try {
Method method = wifimanager.getClass().getDeclaredMethod("isWifiApEnabled");
method.setAccessible(true);
return (Boolean) method.invoke(wifimanager);
}
catch (Throwable ignored) {}
return false;
}
// toggle wifi hotspot on or off
public static boolean configApState(Context context) {
WifiManager wifimanager = (WifiManager) context.getSystemService(context.WIFI_SERVICE);
WifiConfiguration wificonfiguration = null;
try {
// if WiFi is on, turn it off
if(isApOn(context)) {
wifimanager.setWifiEnabled(false);
}
Method method = wifimanager.getClass().getMethod("setWifiApEnabled", WifiConfiguration.class, boolean.class);
method.invoke(wifimanager, wificonfiguration, !isApOn(context));
return true;
}
catch (Exception e) {
e.printStackTrace();
}
return false;
}
} // end of class
You need to add the permissions below to your AndroidMainfest:
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
Use this standalone ApManager class from anywhere as follows:
ApManager.isApOn(YourActivity.this); // check Ap state :boolean
ApManager.configApState(YourActivity.this); // change Ap state :boolean
Hope this will help someone
How to copy files from host to Docker container?
Another solution for copying files into a running container is using tar:
tar -c foo.sh | docker exec -i theDockerContainer /bin/tar -C /tmp -x
Copies the file foo.sh
into /tmp
of the container.
Edit: Remove reduntant -f
, thanks to Maartens comment.
Unable to locate an executable at "/usr/bin/java/bin/java" (-1)
i have experienced the same problem, and after reading this post i have double checked the JAVA_HOME
definition in .bash_profile
. It is actually:
export JAVA_HOME=$(which java)
that, exactly as Anony-Mousse is explaining, is the executable. Changing it to:
export=/Library/Java/Home
fixes the problem, tho is still interesting to understand why it's valued in that way in the profile file.
Non-conformable arrays error in code
The problem is that omega
in your case is matrix
of dimensions 1 * 1
. You should convert it to a vector if you wish to multiply t(X) %*% X
by a scalar (that is omega
)
In particular, you'll have to replace this line:
omega = rgamma(1,a0,1) / L0
with:
omega = as.vector(rgamma(1,a0,1) / L0)
everywhere in your code. It happens in two places (once inside the loop and once outside). You can substitute as.vector(.)
or c(t(.))
. Both are equivalent.
Here's the modified code that should work:
gibbs = function(data, m01 = 0, m02 = 0, k01 = 0.1, k02 = 0.1,
a0 = 0.1, L0 = 0.1, nburn = 0, ndraw = 5000) {
m0 = c(m01, m02)
C0 = matrix(nrow = 2, ncol = 2)
C0[1,1] = 1 / k01
C0[1,2] = 0
C0[2,1] = 0
C0[2,2] = 1 / k02
beta = mvrnorm(1,m0,C0)
omega = as.vector(rgamma(1,a0,1) / L0)
draws = matrix(ncol = 3,nrow = ndraw)
it = -nburn
while (it < ndraw) {
it = it + 1
C1 = solve(solve(C0) + omega * t(X) %*% X)
m1 = C1 %*% (solve(C0) %*% m0 + omega * t(X) %*% y)
beta = mvrnorm(1, m1, C1)
a1 = a0 + n / 2
L1 = L0 + t(y - X %*% beta) %*% (y - X %*% beta) / 2
omega = as.vector(rgamma(1, a1, 1) / L1)
if (it > 0) {
draws[it,1] = beta[1]
draws[it,2] = beta[2]
draws[it,3] = omega
}
}
return(draws)
}
Spring Boot access static resources missing scr/main/resources
Just use Spring type ClassPathResource.
File file = new ClassPathResource("countries.xml").getFile();
As long as this file is somewhere on classpath Spring will find it. This can be src/main/resources
during development and testing. In production, it can be current running directory.
EDIT: This approach doesn't work if file is in fat JAR. In such case you need to use:
InputStream is = new ClassPathResource("countries.xml").getInputStream();
Python Brute Force algorithm
Try this:
import os
import sys
Zeichen=["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"]
def start(): input("Enter to start")
def Gen(stellen): if stellen==1: for i in Zeichen: print(i) elif stellen==2: for i in Zeichen: for r in Zeichen: print(i+r) elif stellen==3: for i in Zeichen: for r in Zeichen: for t in Zeichen: print(i+r+t) elif stellen==4: for i in Zeichen: for r in Zeichen: for t in Zeichen: for u in Zeichen: print(i+r+t+u) elif stellen==5: for i in Zeichen: for r in Zeichen: for t in Zeichen: for u in Zeichen: for o in Zeichen: print(i+r+t+u+o) else: print("done")
#*********************
start()
Gen(1)
Gen(2)
Gen(3)
Gen(4)
Gen(5)
How to link html pages in same or different folders?
Within the same folder, just use the file name:
<a href="thefile.html">my link</a>
Within the parent folder's directory:
<a href="../thefile.html">my link</a>
Within a sub-directory:
<a href="subdir/thefile.html">my link</a>
Django. Override save for model
I have found one another simple way to store the data into the database
models.py
class LinkModel(models.Model):
link = models.CharField(max_length=500)
shortLink = models.CharField(max_length=30,unique=True)
In database I have only 2 variables
views.py
class HomeView(TemplateView):
def post(self,request, *args, **kwargs):
form = LinkForm(request.POST)
if form.is_valid():
text = form.cleaned_data['link'] # text for link
dbobj = LinkModel()
dbobj.link = text
self.no = self.gen.generateShortLink() # no for shortLink
dbobj.shortLink = str(self.no)
dbobj.save() # Saving from views.py
In this I have created the instance of model in views.py only and putting/saving data into 2 variables from views only.
MVC Razor @foreach
When people say don't put logic in views, they're usually referring to business logic, not rendering logic. In my humble opinion, I think using @foreach in views is perfectly fine.
How to list the size of each file and directory and sort by descending size in Bash?
[enhanced version]
This is going to be much faster and precise than the initial version below and will output the sum of all the file size of current directory:
echo `find . -type f -exec stat -c %s {} \; | tr '\n' '+' | sed 's/+$//g'` | bc
the stat -c %s
command on a file will return its size in bytes. The tr
command here is used to overcome xargs
command limitations (apparently piping to xargs
is splitting results on more lines, breaking the logic of my command). Hence tr
is taking care of replacing line feed with +
(plus) sign. sed
has the only goal to remove the last +
sign from the resulting string to avoid complains from the final bc
(basic calculator) command that, as usual, does the math.
Performances: I tested it on several directories and over ~150.000 files top (the current number of files of my fedora 15 box) having what I believe it is an amazing result:
# time echo `find / -type f -exec stat -c %s {} \; | tr '\n' '+' | sed 's/+$//g'` | bc
12671767700
real 2m19.164s
user 0m2.039s
sys 0m14.850s
Just in case you want to make a comparison with the du -sb /
command, it will output an estimated disk usage in bytes (-b
option)
# du -sb /
12684646920 /
As I was expecting it is a little larger than my command calculation because the du
utility returns allocated space of each file and not the actual consumed space.
[initial version]
You cannot use du
command if you need to know the exact sum size of your folder because (as per man page citation) du
estimates file space usage. Hence it will lead you to a wrong result, an approximation (maybe close to the sum size but most likely greater than the actual size you are looking for).
I think there might be different ways to answer your question but this is mine:
ls -l $(find . -type f | xargs) | cut -d" " -f5 | xargs | sed 's/\ /+/g'| bc
It finds all files under . directory (change . with whatever directory you like), also hidden files are included and (using xargs
) outputs their names in a single line, then produces a detailed list using ls -l
. This (sometimes) huge output is piped towards cut command and only the fifth field (-f5
), which is the file size in bytes is taken and again piped against xargs
which produces again a single line of sizes separated by blanks. Now take place a sed magic which replaces each blank space with a plus (+
) sign and finally bc
(basic calculator) does the math.
It might need additional tuning and you may have ls
command complaining about arguments list too long.
HTML5 form validation pattern alphanumeric with spaces?
My solution is to cover all the range of diacritics:
([A-z0-9À-ž\s]){2,}
A-z
- this is for all latin characters
0-9
- this is for all digits
À-ž
- this is for all diacritics
\s
- this is for spaces
{2,}
- string needs to be at least 2 characters long
How do I pass a variable to the layout using Laravel' Blade templating?
In the Blade Template : define a variable like this
@extends('app',['title' => 'Your Title Goes Here'])
@section('content')
And in the app.blade.php or any other of your choice ( I'm just following default Laravel 5 setup )
<title>{{ $title or 'Default title Information if not set explicitly' }}</title>
This is my first answer here. Hope it works.Good luck!
C# List of objects, how do I get the sum of a property
Here is example code you could run to make such test:
var f = 10000000;
var p = new int[f];
for(int i = 0; i < f; ++i)
{
p[i] = i % 2;
}
var time = DateTime.Now;
p.Sum();
Console.WriteLine(DateTime.Now - time);
int x = 0;
time = DateTime.Now;
foreach(var item in p){
x += item;
}
Console.WriteLine(DateTime.Now - time);
x = 0;
time = DateTime.Now;
for(int i = 0, j = f; i < j; ++i){
x += p[i];
}
Console.WriteLine(DateTime.Now - time);
The same example for complex object is:
void Main()
{
var f = 10000000;
var p = new Test[f];
for(int i = 0; i < f; ++i)
{
p[i] = new Test();
p[i].Property = i % 2;
}
var time = DateTime.Now;
p.Sum(k => k.Property);
Console.WriteLine(DateTime.Now - time);
int x = 0;
time = DateTime.Now;
foreach(var item in p){
x += item.Property;
}
Console.WriteLine(DateTime.Now - time);
x = 0;
time = DateTime.Now;
for(int i = 0, j = f; i < j; ++i){
x += p[i].Property;
}
Console.WriteLine(DateTime.Now - time);
}
class Test
{
public int Property { get; set; }
}
My results with compiler optimizations off are:
00:00:00.0570370 : Sum()
00:00:00.0250180 : Foreach()
00:00:00.0430272 : For(...)
and for second test are:
00:00:00.1450955 : Sum()
00:00:00.0650430 : Foreach()
00:00:00.0690510 : For()
it looks like LINQ is generally slower than foreach(...) but what is weird for me is that foreach(...) appears to be faster than for loop.
Adding click event listener to elements with the same class
You should use querySelectorAll
. It returns NodeList, however querySelector
returns only the first found element:
var deleteLink = document.querySelectorAll('.delete');
Then you would loop:
for (var i = 0; i < deleteLink.length; i++) {
deleteLink[i].addEventListener('click', function(event) {
if (!confirm("sure u want to delete " + this.title)) {
event.preventDefault();
}
});
}
Also you should preventDefault only if confirm === false
.
It's also worth noting that return false/true
is only useful for event handlers bound with onclick = function() {...}
. For addEventListening
you should use event.preventDefault()
.
Demo: http://jsfiddle.net/Rc7jL/3/
ES6 version
You can make it a little cleaner (and safer closure-in-loop wise) by using Array.prototype.forEach iteration instead of for-loop:
var deleteLinks = document.querySelectorAll('.delete');
Array.from(deleteLinks).forEach(link => {
link.addEventListener('click', function(event) {
if (!confirm(`sure u want to delete ${this.title}`)) {
event.preventDefault();
}
});
});
Example above uses Array.from and template strings from ES2015 standard.
Manually adding a Userscript to Google Chrome
This parameter is is working for me:
--enable-easy-off-store-extension-install
Do the following:
- Right click on your "Chrome" icon.
- Choose properties
- At the end of your target line, place these parameters:
--enable-easy-off-store-extension-install
- It should look like:
chrome.exe --enable-easy-off-store-extension-install
- Start Chrome by double-clicking on the icon
How can I refresh a page with jQuery?
There are many ways to reload the current pages, but somehow using those approaches you can see page updated but not with few cache values will be there, so overcome that issue or if you wish to make hard requests then use the below code.
location.reload(true);
//Here, it will make a hard request or reload the current page and clear the cache as well.
location.reload(false); OR location.reload();
//It can be reload the page with cache
What is the difference between window, screen, and document in Javascript?
the window
contains everything, so you can call window.screen
and window.document
to get those elements. Check out this fiddle, pretty-printing the contents of each object: http://jsfiddle.net/JKirchartz/82rZu/
You can also see the contents of the object in firebug/dev tools like this:
console.dir(window);
console.dir(document);
console.dir(screen);
window
is the root of everything, screen
just has screen dimensions, and document
is top DOM object. so you can think of it as window
being like a super-document
...
Java - sending HTTP parameters via POST method easily
In a GET request, the parameters are sent as part of the URL.
In a POST request, the parameters are sent as a body of the request, after the headers.
To do a POST with HttpURLConnection, you need to write the parameters to the connection after you have opened the connection.
This code should get you started:
String urlParameters = "param1=a¶m2=b¶m3=c";
byte[] postData = urlParameters.getBytes( StandardCharsets.UTF_8 );
int postDataLength = postData.length;
String request = "http://example.com/index.php";
URL url = new URL( request );
HttpURLConnection conn= (HttpURLConnection) url.openConnection();
conn.setDoOutput( true );
conn.setInstanceFollowRedirects( false );
conn.setRequestMethod( "POST" );
conn.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded");
conn.setRequestProperty( "charset", "utf-8");
conn.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
conn.setUseCaches( false );
try( DataOutputStream wr = new DataOutputStream( conn.getOutputStream())) {
wr.write( postData );
}
Function inside a function.?
function inside a function or so called nested functions are very usable if you need to do some recursion processes such as looping true multiple layer of array or a file tree without multiple loops or sometimes i use it to avoid creating classes for small jobs which require dividing and isolating functionality among multiple functions. but before you go for nested functions you have to understand that
- child function will not be available unless the main function is executed
- Once main function got executed the child functions will be globally available to access
- if you need to call the main function twice it will try to re define the child function and this will throw a fatal error
so is this mean you cant use nested functions? No, you can with the below workarounds
first method is to block the child function being re declaring into global function stack by using conditional block with function exists, this will prevent the function being declared multiple times into global function stack.
function myfunc($a,$b=5){
if(!function_exists("child")){
function child($x,$c){
return $c+$x;
}
}
try{
return child($a,$b);
}catch(Exception $e){
throw $e;
}
}
//once you have invoke the main function you will be able to call the child function
echo myfunc(10,20)+child(10,10);
and the second method will be limiting the function scope of child to local instead of global, to do that you have to define the function as a Anonymous function and assign it to a local variable, then the function will only be available in local scope and will re declared and invokes every time you call the main function.
function myfunc($a,$b=5){
$child = function ($x,$c){
return $c+$x;
};
try{
return $child($a,$b);
}catch(Exception $e){
throw $e;
}
}
echo myfunc(10,20);
remember the child will not be available outside the main function or global function stack
Compare and contrast REST and SOAP web services?
SOAP uses WSDL for communication btw consumer and provider, whereas
REST just uses XML or JSON to send and receive data
WSDL defines contract between client and service and is static by its nature. In case of REST contract is somewhat complicated and is defined by HTTP, URI, Media Formats and Application Specific Coordination Protocol. It's highly dynamic unlike WSDL.
SOAP doesn't return human readable result, whilst REST result is readable with is just plain XML or JSON
This is not true. Plain XML or JSON are not RESTful at all. None of them define any controls(i.e. links and link relations, method information, encoding information etc...) which is against REST as far as messages must be self contained and coordinate interaction between agent/client and service.
With links + semantic link relations clients should be able to determine what is next interaction step and follow these links and continue communication with service.
It is not necessary that messages be human readable, it's possible to use cryptic format and build perfectly valid REST applications. It doesn't matter whether message is human readable or not.
Thus, plain XML(application/xml) or JSON(application/json) are not sufficient formats for building REST applications. It's always reasonable to use subset of these generic media types which have strong semantic meaning and offer enough control information(links etc...) to coordinate interactions between client and server.
REST is over only HTTP
Not true, HTTP is most widely used and when we talk about REST web services we just assume HTTP. HTTP defines interface with it's methods(GET, POST, PUT, DELETE, PATCH etc) and various headers which can be used uniformly for interacting with resources. This uniformity can be achieved with other protocols as well.
P.S.
Very simple, yet very interesting explanation of REST: http://www.looah.com/source/view/2284
Explode PHP string by new line
Place the \n
in double quotes:
explode("\n", $_POST['skuList']);
In single quotes, if I'm not mistaken, this is treated as \
and n
separately.
Accessing constructor of an anonymous class
In my case, a local class (with custom constructor) worked as an anonymous class:
Object a = getClass1(x);
public Class1 getClass1(int x) {
class Class2 implements Class1 {
void someNewMethod(){
}
public Class2(int a){
super();
System.out.println(a);
}
}
Class1 c = new Class2(x);
return c;
}
Pointer to a string in C?
The same notation is used for pointing at a single character or the first character of a null-terminated string:
char c = 'Z';
char a[] = "Hello world";
char *ptr1 = &c;
char *ptr2 = a; // Points to the 'H' of "Hello world"
char *ptr3 = &a[0]; // Also points to the 'H' of "Hello world"
char *ptr4 = &a[6]; // Points to the 'w' of "world"
char *ptr5 = a + 6; // Also points to the 'w' of "world"
The values in ptr2
and ptr3
are the same; so are the values in ptr4
and ptr5
. If you're going to treat some data as a string, it is important to make sure it is null terminated, and that you know how much space there is for you to use. Many problems are caused by not understanding what space is available and not knowing whether the string was properly null terminated.
Note that all the pointers above can be dereferenced as if they were an array:
*ptr1 == 'Z'
ptr1[0] == 'Z'
*ptr2 == 'H'
ptr2[0] == 'H'
ptr2[4] == 'o'
*ptr4 == 'w'
ptr4[0] == 'w'
ptr4[4] == 'd'
ptr5[0] == ptr3[6]
*(ptr5+0) == *(ptr3+6)
Late addition to question
What does char (*ptr)[N];
represent?
This is a more complex beastie altogether. It is a pointer to an array of N
characters. The type is quite different; the way it is used is quite different; the size of the object pointed to is quite different.
char (*ptr)[12] = &a;
(*ptr)[0] == 'H'
(*ptr)[6] == 'w'
*(*ptr + 6) == 'w'
Note that ptr + 1
points to undefined territory, but points 'one array of 12 bytes' beyond the start of a
. Given a slightly different scenario:
char b[3][12] = { "Hello world", "Farewell", "Au revoir" };
char (*pb)[12] = &b[0];
Now:
(*(pb+0))[0] == 'H'
(*(pb+1))[0] == 'F'
(*(pb+2))[5] == 'v'
You probably won't come across pointers to arrays except by accident for quite some time; I've used them a few times in the last 25 years, but so few that I can count the occasions on the fingers of one hand (and several of those have been answering questions on Stack Overflow). Beyond knowing that they exist, that they are the result of taking the address of an array, and that you probably didn't want it, you don't really need to know more about pointers to arrays.
Is there anyway to exclude artifacts inherited from a parent POM?
Some ideas:
Maybe you could simply not inherit from the parent in that case (and declare a dependency on base
with the exclusion). Not handy if you have lot of stuff in the parent pom.
Another thing to test would be to declare the mail
artifact with the version required by ALL-DEPS
under the dependencyManagement
in the parent pom to force the convergence (although I'm not sure this will solve the scoping problem).
<dependencyManagement>
<dependencies>
<dependency>
<groupId>javax.mail</groupId>
<artifactId>mail</artifactId>
<version>???</version><!-- put the "right" version here -->
</dependency>
</dependencies>
</dependencyManagement>
- Or you could exclude the
mail
dependency from log4j if you're not using the features relying on it (and this is what I would do):
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.15</version>
<scope>provided</scope>
<exclusions>
<exclusion>
<groupId>javax.mail</groupId>
<artifactId>mail</artifactId>
</exclusion>
<exclusion>
<groupId>javax.jms</groupId>
<artifactId>jms</artifactId>
</exclusion>
<exclusion>
<groupId>com.sun.jdmk</groupId>
<artifactId>jmxtools</artifactId>
</exclusion>
<exclusion>
<groupId>com.sun.jmx</groupId>
<artifactId>jmxri</artifactId>
</exclusion>
</exclusions>
</dependency>
- Or you could revert to the version 1.2.14 of log4j instead of the heretic 1.2.15 version (why didn't they mark the above dependencies as optional?!).
How to test the type of a thrown exception in Jest
I haven't tried it myself, but I would suggest using Jest's toThrow assertion. So I guess your example would look something like this:
it('should throw Error with message \'UNKNOWN ERROR\' when no parameters were passed', (t) => {
const error = t.throws(() => {
throwError();
}, TypeError);
expect(t).toThrowError('UNKNOWN ERROR');
//or
expect(t).toThrowError(TypeError);
});
Again, I haven't test it, but I think it should work.
Java: Why is the Date constructor deprecated, and what do I use instead?
tl;dr
LocalDate.of( 1985 , 1 , 1 )
…or…
LocalDate.of( 1985 , Month.JANUARY , 1 )
Details
The java.util.Date
, java.util.Calendar
, and java.text.SimpleDateFormat
classes were rushed too quickly when Java first launched and evolved. The classes were not well designed or implemented. Improvements were attempted, thus the deprecations you’ve found. Unfortunately the attempts at improvement largely failed. You should avoid these classes altogether. They are supplanted in Java 8 by new classes.
Problems In Your Code
A java.util.Date has both a date and a time portion. You ignored the time portion in your code. So the Date class will take the beginning of the day as defined by your JVM’s default time zone and apply that time to the Date object. So the results of your code will vary depending on which machine it runs or which time zone is set. Probably not what you want.
If you want just the date, without the time portion, such as for a birth date, you may not want to use a Date
object. You may want to store just a string of the date, in ISO 8601 format of YYYY-MM-DD
. Or use a LocalDate
object from Joda-Time (see below).
Joda-Time
First thing to learn in Java: Avoid the notoriously troublesome java.util.Date & java.util.Calendar classes bundled with Java.
As correctly noted in the answer by user3277382, use either Joda-Time or the new java.time.* package in Java 8.
Example Code in Joda-Time 2.3
DateTimeZone timeZoneNorway = DateTimeZone.forID( "Europe/Oslo" );
DateTime birthDateTime_InNorway = new DateTime( 1985, 1, 1, 3, 2, 1, timeZoneNorway );
DateTimeZone timeZoneNewYork = DateTimeZone.forID( "America/New_York" );
DateTime birthDateTime_InNewYork = birthDateTime_InNorway.toDateTime( timeZoneNewYork );
DateTime birthDateTime_UtcGmt = birthDateTime_InNorway.toDateTime( DateTimeZone.UTC );
LocalDate birthDate = new LocalDate( 1985, 1, 1 );
Dump to console…
System.out.println( "birthDateTime_InNorway: " + birthDateTime_InNorway );
System.out.println( "birthDateTime_InNewYork: " + birthDateTime_InNewYork );
System.out.println( "birthDateTime_UtcGmt: " + birthDateTime_UtcGmt );
System.out.println( "birthDate: " + birthDate );
When run…
birthDateTime_InNorway: 1985-01-01T03:02:01.000+01:00
birthDateTime_InNewYork: 1984-12-31T21:02:01.000-05:00
birthDateTime_UtcGmt: 1985-01-01T02:02:01.000Z
birthDate: 1985-01-01
java.time
In this case the code for java.time is nearly identical to that of Joda-Time.
We get a time zone (ZoneId
), and construct a date-time object assigned to that time zone (ZonedDateTime
). Then using the Immutable Objects pattern, we create new date-times based on the old object’s same instant (count of nanoseconds since epoch) but assigned other time zone. Lastly we get a LocalDate
which has no time-of-day nor time zone though notice the time zone applies when determining that date (a new day dawns earlier in Oslo than in New York for example).
ZoneId zoneId_Norway = ZoneId.of( "Europe/Oslo" );
ZonedDateTime zdt_Norway = ZonedDateTime.of( 1985 , 1 , 1 , 3 , 2 , 1 , 0 , zoneId_Norway );
ZoneId zoneId_NewYork = ZonedId.of( "America/New_York" );
ZonedDateTime zdt_NewYork = zdt_Norway.withZoneSameInstant( zoneId_NewYork );
ZonedDateTime zdt_Utc = zdt_Norway.withZoneSameInstant( ZoneOffset.UTC ); // Or, next line is similar.
Instant instant = zdt_Norway.toInstant(); // Instant is always in UTC.
LocalDate localDate_Norway = zdt_Norway.toLocalDate();
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date
, Calendar
, & SimpleDateFormat
.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.*
classes.
Where to obtain the java.time classes?
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval
, YearWeek
, YearQuarter
, and more.
Adding +1 to a variable inside a function
points
is not within the function's scope. You can grab a reference to the variable by using nonlocal:
points = 0
def test():
nonlocal points
points += 1
If points
inside test()
should refer to the outermost (module) scope, use global:
points = 0
def test():
global points
points += 1
Align contents inside a div
You can do it like this also:
HTML
<body>
<div id="wrapper_1">
<div id="container_1"></div>
</div>
</body>
CSS
body { width: 100%; margin: 0; padding: 0; overflow: hidden; }
#wrapper_1 { clear: left; float: left; position: relative; left: 50%; }
#container_1 { display: block; float: left; position: relative; right: 50%; }
As Artem Russakovskii mentioned also, read the original article by Mattew James Taylor for full description.
How to trigger click event on href element
The native DOM method does the right thing:
$('.cssbuttongo')[0].click();
^
Important!
This works regardless of whether the href
is a URL, a fragment (e.g. #blah
) or even a javascript:
.
Note that this calls the DOM click
method instead of the jQuery click
method (which is very incomplete and completely ignores href
).
How to define the basic HTTP authentication using cURL correctly?
curl -u username:password http://
curl -u username http://
From the documentation page:
-u, --user <user:password>
Specify the user name and password to use for server authentication.
Overrides -n, --netrc and --netrc-optional.
If you simply specify the user name, curl will prompt for a password.
The user name and passwords are split up on the first colon, which
makes it impossible to use a colon in the user name with this option.
The password can, still.
When using Kerberos V5 with a Windows based server you should include
the Windows domain name in the user name, in order for the server to
succesfully obtain a Kerberos Ticket. If you don't then the initial
authentication handshake may fail.
When using NTLM, the user name can be specified simply as the user
name, without the domain, if there is a single domain and forest in
your setup for example.
To specify the domain name use either Down-Level Logon Name or UPN
(User Principal Name) formats. For example, EXAMPLE\user and
[email protected] respectively.
If you use a Windows SSPI-enabled curl binary and perform Kerberos V5,
Negotiate, NTLM or Digest authentication then you can tell curl to
select the user name and password from your environment by specifying
a single colon with this option: "-u :".
If this option is used several times, the last one will be used.
http://curl.haxx.se/docs/manpage.html#-u
Note that you do not need --basic
flag as it is the default.
How can I multiply all items in a list together with Python?
I would like this in following way:
def product_list(p):
total =1 #critical step works for all list
for i in p:
total=total*i # this will ensure that each elements are multiplied by itself
return total
print product_list([2,3,4,2]) #should print 48
Speed tradeoff of Java's -Xms and -Xmx options
This was always the question I had when I was working on one of my application which created massive number of threads per request.
So this is a really good question and there are two aspects of this:
1. Whether my Xms and Xmx value should be same
- Most websites and even oracle docs suggest it to be the same. However, I suggest to have some 10-20% of buffer between those values to give heap resizing an option to your application in case sudden high traffic spikes OR a incidental memory leak.
2. Whether I should start my Application with lower heap size
- So here's the thing - no matter what GC Algo you use (even G1), large heap always has some trade off. The goal is to identify the behavior of your application to what heap size you can allow your GC pauses in terms of latency and throughput.
- For example, if your application has lot of threads (each thread has 1 MB stack in native memory and not in heap) but does not occupy heavy object space, then I suggest have a lower value of Xms.
- If your application creates lot of objects with increasing number of threads, then identify to what value of Xms you can set to tolerate those STW pauses. This means identify the max response time of your incoming requests you can tolerate and according tune the minimum heap size.
How to set a cell to NaN in a pandas dataframe
While using replace
seems to solve the problem, I would like to propose an alternative. Problem with mix of numeric and some string values in the column not to have strings replaced with np.nan, but to make whole column proper. I would bet that original column most likely is of an object type
Name: y, dtype: object
What you really need is to make it a numeric column (it will have proper type and would be quite faster), with all non-numeric values replaced by NaN.
Thus, good conversion code would be
pd.to_numeric(df['y'], errors='coerce')
Specify errors='coerce'
to force strings that can't be parsed to a numeric value to become NaN. Column type would be
Name: y, dtype: float64
Showing loading animation in center of page while making a call to Action method in ASP .NET MVC
You can do this by displaying a div (if you want to do it in a modal manner you could use blockUI - or one of the many other modal dialog plugins out there) prior to the request then just waiting until the call back succeeds as a quick example you can you $.getJSON as follows (you might want to use .ajax if you want to add proper error handling)
$("#ajaxLoader").show(); //Or whatever you want to do
$.getJSON("/AJson/Call/ThatTakes/Ages", function(result) {
//Process your response
$("#ajaxLoader").hide();
});
If you do this several times in your app and want to centralise the behaviour for all ajax calls you can make use of the global AJAX events:-
$("#ajaxLoader").ajaxStart(function() { $(this).show(); })
.ajaxStop(function() { $(this).hide(); });
Using blockUI is similar for example with mark up like:-
<a href="/Path/ToYourJson/Action" id="jsonLink">Get JSON</a>
<div id="resultContainer" style="display:none">
And the answer is:-
<p id="result"></p>
</div>
<div id="ajaxLoader" style="display:none">
<h2>Please wait</h2>
<p>I'm getting my AJAX on!</p>
</div>
And using jQuery:-
$(function() {
$("#jsonLink").click(function(e) {
$.post(this.href, function(result) {
$("#resultContainer").fadeIn();
$("#result").text(result.Answer);
}, "json");
return false;
});
$("#ajaxLoader").ajaxStart(function() {
$.blockUI({ message: $("#ajaxLoader") });
})
.ajaxStop(function() {
$.unblockUI();
});
});
How to use View.OnTouchListener instead of onClick
The event when user releases his finger is MotionEvent.ACTION_UP
. I'm not aware if there are any guidelines which prohibit using View.OnTouchListener instead of onClick(), most probably it depends of situation.
Here's a sample code:
imageButton.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if(event.getAction() == MotionEvent.ACTION_UP){
// Do what you want
return true;
}
return false;
}
});
The CodeDom provider type "Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider" could not be located
In our case we are using ToroiseSVN and it seems by default the bin folder is not added to the sourcecontrol. So when updating the website on the production server the bin folder was not added to it, thus resulting in this exception.
To add the bin folder to SVN go to the folder on the hdd and find the bin folder. Right click it and select TortoiseSVN --> Add
Now update the repository to include the newly added files and update the production server next. All should be well now.
How do I disable a Pylint warning?
Starting from Pylint v. 0.25.3, you can use the symbolic names for disabling warnings instead of having to remember all those code numbers. E.g.:
# pylint: disable=locally-disabled, multiple-statements, fixme, line-too-long
This style is more instructive than cryptic error codes, and also more practical since newer versions of Pylint only output the symbolic name, not the error code.
The correspondence between symbolic names and codes can be found here.
A disable comment can be inserted on its own line, applying the disable to everything that comes after in the same block. Alternatively, it can be inserted at the end of the line for which it is meant to apply.
If Pylint outputs "Locally disabling
" messages, you can get rid of them by including the disable locally-disabled
first as in the example above.
Finding an element in an array in Java
There is a contains
method for lists, so you should be able to do:
Arrays.asList(yourArray).contains(yourObject);
Warning: this might not do what you (or I) expect, see Tom's comment below.
Execute JavaScript using Selenium WebDriver in C#
The object, method, and property names in the .NET language bindings do not exactly correspond to those in the Java bindings. One of the principles of the project is that each language binding should "feel natural" to those comfortable coding in that language. In C#, the code you'd want for executing JavaScript is as follows
IWebDriver driver; // assume assigned elsewhere
IJavaScriptExecutor js = (IJavaScriptExecutor)driver;
string title = (string)js.ExecuteScript("return document.title");
Note that the complete documentation of the WebDriver API for .NET can be found at this link.
Angular CLI SASS options
CSS Preprocessor integration
Angular CLI supports all major CSS preprocessors:
To use these preprocessors simply add the file to your component's styleUrls:
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent {
title = 'app works!';
}
When generating a new project you can also define which extension you want for style files:
ng new sassy-project --style=sass
Or set the default style on an existing project:
ng config schematics.@schematics/angular:component.styleext scss
note: @schematics/angular is the default schematic for the Angular CLI
Style strings added to the @Component.styles array must be written in CSS because the CLI cannot apply a pre-processor to inline styles.
Based on angular documentation
https://github.com/angular/angular-cli/wiki/stories-css-preprocessors
Select folder dialog WPF
I wrote about it on my blog a long time ago, WPF's support for common file dialogs is really bad (or at least is was in 3.5 I didn't check in version 4) - but it's easy to work around it.
You need to add the correct manifest to your application - that will give you a modern style message boxes and folder browser (WinForms FolderBrowserDialog) but not WPF file open/save dialogs, this is described in those 3 posts (if you don't care about the explanation and only want the solution go directly to the 3rd):
Fortunately, the open/save dialogs are very thin wrappers around the Win32 API that is easy to call with the right flags to get the Vista/7 style (after setting the manifest)
Date vs DateTime
I created a simple Date struct for times when you need a simple date without worrying about time portion, timezones, local vs. utc, etc.
Date today = Date.Today;
Date yesterday = Date.Today.AddDays(-1);
Date independenceDay = Date.Parse("2013-07-04");
independenceDay.ToLongString(); // "Thursday, July 4, 2013"
independenceDay.ToShortString(); // "7/4/2013"
independenceDay.ToString(); // "7/4/2013"
independenceDay.ToString("s"); // "2013-07-04"
int july = independenceDay.Month; // 7
https://github.com/claycephus/csharp-date
How to select multiple files with <input type="file">?
Copy and paste this into your html:
<input type="file" id="files" name="files[]" multiple />
<output id="list"></output>
<script>
function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
// files is a FileList of File objects. List some properties.
var output = [];
for (var i = 0, f; f = files[i]; i++) {
output.push('<li><strong>', escape(f.name), '</strong> (', f.type || 'n/a', ') - ',
f.size, ' bytes, last modified: ',
f.lastModifiedDate ? f.lastModifiedDate.toLocaleDateString() : 'n/a',
'</li>');
}
document.getElementById('list').innerHTML = '<ul>' + output.join('') + '</ul>';
}
This comes to you, through me, from this webpage: http://www.html5rocks.com/en/tutorials/file/dndfiles/
How does the @property decorator work in Python?
Let's start with Python decorators.
A Python decorator is a function that helps to add some additional functionalities to an already defined function.
In Python, everything is an object. Functions in Python are first-class objects which means that they can be referenced by a variable, added in the lists, passed as arguments to another function etc.
Consider the following code snippet.
def decorator_func(fun):
def wrapper_func():
print("Wrapper function started")
fun()
print("Given function decorated")
# Wrapper function add something to the passed function and decorator
# returns the wrapper function
return wrapper_func
def say_bye():
print("bye!!")
say_bye = decorator_func(say_bye)
say_bye()
# Output:
# Wrapper function started
# bye
# Given function decorated
Here, we can say that decorator function modified our say_hello function and added some extra lines of code in it.
Python syntax for decorator
def decorator_func(fun):
def wrapper_func():
print("Wrapper function started")
fun()
print("Given function decorated")
# Wrapper function add something to the passed function and decorator
# returns the wrapper function
return wrapper_func
@decorator_func
def say_bye():
print("bye!!")
say_bye()
Let's Concluded everything than with a case scenario, but before that let's talk about some oops priniciples.
Getters and setters are used in many object oriented programming languages to ensure the principle of data encapsulation(is seen as the bundling of data with the methods that operate on these data.)
These methods are of course the getter for retrieving the data and the setter for changing the data.
According to this principle, the attributes of a class are made private to hide and protect them from other code.
Yup, @property is basically a pythonic way to use getters and setters.
Python has a great concept called property which makes the life of an object-oriented programmer much simpler.
Let us assume that you decide to make a class that could store the temperature in degree Celsius.
class Celsius:
def __init__(self, temperature = 0):
self.set_temperature(temperature)
def to_fahrenheit(self):
return (self.get_temperature() * 1.8) + 32
def get_temperature(self):
return self._temperature
def set_temperature(self, value):
if value < -273:
raise ValueError("Temperature below -273 is not possible")
self._temperature = value
Refactored Code, Here is how we could have achieved it with property.
In Python, property() is a built-in function that creates and returns a property object.
A property object has three methods, getter(), setter(), and delete().
class Celsius:
def __init__(self, temperature = 0):
self.temperature = temperature
def to_fahrenheit(self):
return (self.temperature * 1.8) + 32
def get_temperature(self):
print("Getting value")
return self.temperature
def set_temperature(self, value):
if value < -273:
raise ValueError("Temperature below -273 is not possible")
print("Setting value")
self.temperature = value
temperature = property(get_temperature,set_temperature)
Here,
temperature = property(get_temperature,set_temperature)
could have been broken down as,
# make empty property
temperature = property()
# assign fget
temperature = temperature.getter(get_temperature)
# assign fset
temperature = temperature.setter(set_temperature)
Point To Note:
- get_temperature remains a property instead of a method.
Now you can access the value of temperature by writing.
C = Celsius()
C.temperature
# instead of writing C.get_temperature()
We can further go on and not define names get_temperature and set_temperature as they are unnecessary and pollute the class namespace.
The pythonic way to deal with the above problem is to use @property.
class Celsius:
def __init__(self, temperature = 0):
self.temperature = temperature
def to_fahrenheit(self):
return (self.temperature * 1.8) + 32
@property
def temperature(self):
print("Getting value")
return self.temperature
@temperature.setter
def temperature(self, value):
if value < -273:
raise ValueError("Temperature below -273 is not possible")
print("Setting value")
self.temperature = value
Points to Note -
- A method which is used for getting a value is decorated with "@property".
- The method which has to function as the setter is decorated with "@temperature.setter", If the function had been called "x", we would have to decorate it with "@x.setter".
- We wrote "two" methods with the same name and a different number of parameters "def temperature(self)" and "def temperature(self,x)".
As you can see, the code is definitely less elegant.
Now,let's talk about one real-life practical scenerio.
Let's say you have designed a class as follows:
class OurClass:
def __init__(self, a):
self.x = a
y = OurClass(10)
print(y.x)
Now, let's further assume that our class got popular among clients and they started using it in their programs, They did all kinds of assignments to the object.
And One fateful day, a trusted client came to us and suggested that "x" has to be a value between 0 and 1000, this is really a horrible scenario!
Due to properties it's easy: We create a property version of "x".
class OurClass:
def __init__(self,x):
self.x = x
@property
def x(self):
return self.__x
@x.setter
def x(self, x):
if x < 0:
self.__x = 0
elif x > 1000:
self.__x = 1000
else:
self.__x = x
This is great, isn't it: You can start with the simplest implementation imaginable, and you are free to later migrate to a property version without having to change the interface! So properties are not just a replacement for getters and setter!
You can check this Implementation here
Why should C++ programmers minimize use of 'new'?
Objects created by new
must be eventually delete
d lest they leak. The destructor won't be called, memory won't be freed, the whole bit. Since C++ has no garbage collection, it's a problem.
Objects created by value (i. e. on stack) automatically die when they go out of scope. The destructor call is inserted by the compiler, and the memory is auto-freed upon function return.
Smart pointers like unique_ptr
, shared_ptr
solve the dangling reference problem, but they require coding discipline and have other potential issues (copyability, reference loops, etc.).
Also, in heavily multithreaded scenarios, new
is a point of contention between threads; there can be a performance impact for overusing new
. Stack object creation is by definition thread-local, since each thread has its own stack.
The downside of value objects is that they die once the host function returns - you cannot pass a reference to those back to the caller, only by copying, returning or moving by value.
Which selector do I need to select an option by its text?
None of the previous suggestions worked for me in jQuery 1.7.2 because I'm trying to set the selected index of the list based on the value from a textbox, and some text values are contained in multiple options. I ended up using the following:
$('#mySelect option:contains(' + value + ')').each(function(){
if ($(this).text() == value) {
$(this).attr('selected', 'selected');
return false;
}
return true;
});
Ajax Upload image
Here is simple way using HTML5 and jQuery:
1) include two JS file
<script src="jslibs/jquery.js" type="text/javascript"></script>
<script src="jslibs/ajaxupload-min.js" type="text/javascript"></script>
2) include CSS to have cool buttons
<link rel="stylesheet" href="css/baseTheme/style.css" type="text/css" media="all" />
3) create DIV or SPAN
<div class="demo" > </div>
4) write this code in your HTML page
$('.demo').ajaxupload({
url:'upload.php'
});
5) create you upload.php file to have PHP code to upload data.
You can download required JS file from here
Here is Example
Its too cool and too fast And easy too! :)
connecting MySQL server to NetBeans
Fist of all make sure your SQL server is running. Actually I'm working on windows and I have installed a nice tool which is called MySQL workbench (you can find it here for almost any platform ).
Thus I just create a new database to test the connection, let's call it stackoverflow, with one table called user.
SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0;
SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;
SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='TRADITIONAL,ALLOW_INVALID_DATES';
DROP SCHEMA IF EXISTS `stackoverflow` ;
CREATE SCHEMA IF NOT EXISTS `stackoverflow` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci ;
USE `stackoverflow` ;
-- -----------------------------------------------------
-- Table `stackoverflow`.`user`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `stackoverflow`.`user` ;
CREATE TABLE IF NOT EXISTS `stackoverflow`.`user` (
`iduser` INT NOT NULL AUTO_INCREMENT,
`name` VARCHAR(75) NOT NULL,
`email` VARCHAR(150) NOT NULL,
PRIMARY KEY (`iduser`),
UNIQUE INDEX `iduser_UNIQUE` (`iduser` ASC),
UNIQUE INDEX `email_UNIQUE` (`email` ASC))
ENGINE = InnoDB;
SET SQL_MODE=@OLD_SQL_MODE;
SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;
SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS;
You can reduce important part to
CREATE SCHEMA IF NOT EXISTS `stackoverflow`
CREATE TABLE IF NOT EXISTS `stackoverflow`.`user` (
`iduser` INT NOT NULL AUTO_INCREMENT,
`name` VARCHAR(75) NOT NULL,
`email` VARCHAR(150) NOT NULL,
PRIMARY KEY (`iduser`),
UNIQUE INDEX `iduser_UNIQUE` (`iduser` ASC),
UNIQUE INDEX `email_UNIQUE` (`email` ASC))
So now I have my brand new stackoverflow database. Let's connect to it throught Netbeans. Launch netbeans and go to the services panel
Now right click on databases: new connection.. Choose MySql connector, they already come packed with netbeans.
Then fill in the gaps the data you need. As shown in the picture add the database name and remove from the connection url the optional parameters as l?zeroDateTimeBehaviour=convertToNull
. Use the right user name and password and test the connection.
As you can see connection is successful.
Click FINISH.
You will have your connection successfully working and available under the services.
Javascript format date / time
For the date part:(month is 0-indexed while days are 1-indexed)
var date = new Date('2014-8-20');
console.log((date.getMonth()+1) + '/' + date.getDate() + '/' + date.getFullYear());
for the time you'll want to create a function to test different situations and convert.
jQuery slide left and show
You can add new function to your jQuery library by adding these line on your own script file and you can easily use fadeSlideRight()
and fadeSlideLeft()
.
Note: you can change width of animation as you like instance of 750px.
$.fn.fadeSlideRight = function(speed,fn) {
return $(this).animate({
'opacity' : 1,
'width' : '750px'
},speed || 400, function() {
$.isFunction(fn) && fn.call(this);
});
}
$.fn.fadeSlideLeft = function(speed,fn) {
return $(this).animate({
'opacity' : 0,
'width' : '0px'
},speed || 400,function() {
$.isFunction(fn) && fn.call(this);
});
}
How to subtract n days from current date in java?
for future use find day of the week ,deduct day and display the deducted day using date.
public static void main(String args[]) throws ParseException {
String[] days = { "Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday" };
SimpleDateFormat format1 = new SimpleDateFormat("dd/MM/yyyy");
Date dt1 = format1.parse("20/10/2013");
Calendar c = Calendar.getInstance();
c.setTime(dt1);
int dayOfWeek = c.get(Calendar.DAY_OF_WEEK);
long diff = Calendar.getInstance().getTime().getTime() ;
System.out.println(dayOfWeek);
switch (dayOfWeek) {
case 6:
System.out.println(days[dayOfWeek - 1]);
break;
case 5:
System.out.println(days[dayOfWeek - 1]);
break;
case 4:
System.out.println(days[dayOfWeek - 1]);
break;
case 3:
System.out.println(days[dayOfWeek - 1]);
break;
case 2:
System.out.println(days[dayOfWeek - 1]);
break;
case 1:
System.out.println(days[dayOfWeek - 1]);
diff = diff -(dt1.getTime()- 3 );
long valuebefore = dt1.getTime();
long valueafetr = dt1.getTime()-2;
System.out.println("DATE IS befor subtraction :"+valuebefore);
System.out.println("DATE IS after subtraction :"+valueafetr);
long x= dt1.getTime()-(2 * 24 * 3600 * 1000);
System.out.println("Deducted date to find firday is - 2 days form Sunday :"+new Date((dt1.getTime()-(2*24*3600*1000))));
System.out.println("DIffrence from now on is :"+diff);
if(diff > 0) {
diff = diff / (1000 * 60 * 60 * 24);
System.out.println("Diff"+diff);
System.out.println("Date is Expired!"+(dt1.getTime() -(long)2));
}
break;
}
}
Font size relative to the user's screen resolution?
New Way
There are several ways to achieve this.
CSS3 supports new dimensions that are relative to view port. But this doesn't work in android.
- 3.2vw = 3.2% of width of viewport
- 3.2vh = 3.2% of height of viewport
- 3.2vmin = Smaller of 3.2vw or 3.2vh
3.2vmax = Bigger of 3.2vw or 3.2vh
body
{
font-size: 3.2vw;
}
see css-tricks.com/.... and also look at caniuse.com/....
Old Way
Use media query but requires font sizes for several breakpoints
body
{
font-size: 22px;
}
h1
{
font-size:44px;
}
@media (min-width: 768px)
{
body
{
font-size: 17px;
}
h1
{
font-size:24px;
}
}
Use dimensions in % or rem. Just change the base font size everything will change. Unlike previous one you could just change the body font and not h1 everytime or let base font size to default of the device and rest all in em.
“Root Ems”(rem): The “rem” is a scalable unit. 1rem is equal to the font-size of the body/html, for instance, if the font-size of the document is 12pt, 1em is equal to 12pt. Root Ems are scalable in nature, so 2em would equal 24pt, .5em would equal 6pt, etc..
Percent (%): The percent unit is much like the “em” unit, save for a few fundamental differences. First and foremost, the current font-size is equal to 100% (i.e. 12pt = 100%). While using the percent unit, your text remains fully scalable for mobile devices and for accessibility.
see kyleschaeffer.com/....
html select only one checkbox in a group
If someone need a solution without an external javascript libraries you could use this example. A group of checkboxes allowing 0..1 values. You may click on the checkbox component or associated label text.
<input id="mygroup1" name="mygroup" type="checkbox" value="1" onclick="toggleRadioCheckbox(this)" /> <label for="mygroup1">Yes</label>
<input id="mygroup0" name="mygroup" type="checkbox" value="0" onclick="toggleRadioCheckbox(this)" /> <label for="mygroup0">No</label>
- - - - - - - -
function toggleRadioCheckbox(sender) {
// RadioCheckbox: 0..1 enabled in a group
if (!sender.checked) return;
var fields = document.getElementsByName(sender.name);
for(var idx=0; idx<fields.length; idx++) {
var field = fields[idx];
if (field.checked && field!=sender)
field.checked=false;
}
}
Length of string in bash
I wanted the simplest case, finally this is a result:
echo -n 'Tell me the length of this sentence.' | wc -m;
36
How to set CATALINA_HOME variable in windows 7?
Setting the JAVA_HOME
, CATALINA_HOME
Environment Variable on Windows
One can do using command prompt:
set JAVA_HOME=C:\ "top level directory of your java install"
set CATALINA_HOME=C:\ "top level directory of your Tomcat install"
set PATH=%PATH%;%JAVA_HOME%\bin;%CATALINA_HOME%\bin
OR you can do the same:
- Go to system properties
- Go to environment variables and add a new variable with the name
JAVA_HOME
and provide variable value as C:\ "top level directory of your java install"
- Go to environment variables and add a new variable with the name
CATALINA_HOME
and provide variable value as C:\ "top level directory of your Tomcat install"
- In path variable add a new variable value as
;%CATALINA_HOME%\bin;
Maximum number of threads per process in Linux?
You can see the current value by the following command-
cat /proc/sys/kernel/threads-max
You can also set the value like
echo 100500 > /proc/sys/kernel/threads-max
The value you set would be checked against the available RAM pages. If the thread structures occupies more than 1/8th) of the available RAM pages, thread-max would be reduced accordingly.
Open a facebook link by native Facebook app on iOS
I know the question is old, but in support of the above answers i wanted to share my working code.
Just add these two methods to whatever class.The code checks if facebook app is installed, if not installed the url is opened in a browser.And if any errors occur when trying to find the profileId, the page will be opened in a browser. Just pass the url(example, http://www.facebook.com/AlibabaUS) to openUrl: and it will do all the magic. Hope it helps someone!.
NOTE: UrlUtils was the class that had the code for me, you might have to change it to something else to suite your needs.
+(void) openUrlInBrowser:(NSString *) url
{
if (url.length > 0) {
NSURL *linkUrl = [NSURL URLWithString:url];
[[UIApplication sharedApplication] openURL:linkUrl];
}
}
+(void) openUrl:(NSString *) urlString
{
//check if facebook app exists
if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"fb://"]]) {
// Facebook app installed
NSArray *tokens = [urlString componentsSeparatedByString:@"/"];
NSString *profileName = [tokens lastObject];
//call graph api
NSURL *apiUrl = [NSURL URLWithString:[NSString stringWithFormat:@"https://graph.facebook.com/%@",profileName]];
NSData *apiResponse = [NSData dataWithContentsOfURL:apiUrl];
NSError *error = nil;
NSDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:apiResponse options:NSJSONReadingMutableContainers error:&error];
//check for parse error
if (error == nil) {
NSString *profileId = [jsonDict objectForKey:@"id"];
if (profileId.length > 0) {//make sure id key is actually available
NSURL *fbUrl = [NSURL URLWithString:[NSString stringWithFormat:@"fb://profile/%@",profileId]];
[[UIApplication sharedApplication] openURL:fbUrl];
}
else{
[UrlUtils openUrlInBrowser:urlString];
}
}
else{//parse error occured
[UrlUtils openUrlInBrowser:urlString];
}
}
else{//facebook app not installed
[UrlUtils openUrlInBrowser:urlString];
}
}
Only numbers. Input number in React
Here's my solution of plain Javascript
Attach a keyup
event to the input
field of your choice - id
in this example.
In the event-handler function just test the key of event.key
with the given regex.
In this case if it doesn't match we prevent the default action of the element - so a "wrong" key-press within the input box won't be registered thus it will never appear in the input box.
let idField = document.getElementById('id');
idField.addEventListener('keypress', function(event) {
if (! /([0-9])/g.test(event.key)) {
event.preventDefault();
}
});
The benefit of this solution may be its flexible nature and by changing and/or logically chaining regular expression(s) can fit many requirements.
E.g. the regex /([a-z0-9-_])/g
should match only lowercase English alphanumeric characters with no spaces and only -
and _
allowed.
Note: that if you use /[a-z]/gi
(note the i at the end) will ignore
letter case and will still accept capital letters.
Is it possible to declare a variable in Gradle usable in Java?
An example of usage an Api App Key in an Android application (Java and XML)
gradle.properties
AppKey="XXXX-XXXX"
build.gradle
buildTypes {
//...
buildTypes.each {
it.buildConfigField 'String', 'APP_KEY_1', AppKey
it.resValue 'string', 'APP_KEY_2', AppKey
}
}
Usage in java code
Log.d("UserActivity", "onCreate, APP_KEY: " + getString(R.string.APP_KEY_2));
BuildConfig.APP_KEY_1
Usage in xml code
<data android:scheme="@string/APP_KEY_2" />
Batch Renaming of Files in a Directory
Be in the directory where you need to perform the renaming.
import os
# get the file name list to nameList
nameList = os.listdir()
#loop through the name and rename
for fileName in nameList:
rename=fileName[15:28]
os.rename(fileName,rename)
#example:
#input fileName bulk like :20180707131932_IMG_4304.JPG
#output renamed bulk like :IMG_4304.JPG
Only allow specific characters in textbox
Intercept the KeyPressed event is in my opinion a good solid solution. Pay attention to trigger code characters (e.KeyChar lower then 32) if you use a RegExp.
But in this way is still possible to inject characters out of range whenever the user paste text from the clipboard. Unfortunately I did not found correct clipboard events to fix this.
So a waterproof solution is to intercept TextBox.TextChanged. Here is sometimes the original out of range character visible, for a short time. I recommend to implement both.
using System.Text.RegularExpressions;
private void Form1_Shown(object sender, EventArgs e)
{
filterTextBoxContent(textBox1);
}
string pattern = @"[^0-9^+^\-^/^*^(^)]";
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if(e.KeyChar >= 32 && Regex.Match(e.KeyChar.ToString(), pattern).Success) { e.Handled = true; }
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
filterTextBoxContent(textBox1);
}
private bool filterTextBoxContent(TextBox textBox)
{
string text = textBox.Text;
MatchCollection matches = Regex.Matches(text, pattern);
bool matched = false;
int selectionStart = textBox.SelectionStart;
int selectionLength = textBox.SelectionLength;
int leftShift = 0;
foreach (Match match in matches)
{
if (match.Success && match.Captures.Count > 0)
{
matched = true;
Capture capture = match.Captures[0];
int captureLength = capture.Length;
int captureStart = capture.Index - leftShift;
int captureEnd = captureStart + captureLength;
int selectionEnd = selectionStart + selectionLength;
text = text.Substring(0, captureStart) + text.Substring(captureEnd, text.Length - captureEnd);
textBox.Text = text;
int boundSelectionStart = selectionStart < captureStart ? -1 : (selectionStart < captureEnd ? 0 : 1);
int boundSelectionEnd = selectionEnd < captureStart ? -1 : (selectionEnd < captureEnd ? 0 : 1);
if (boundSelectionStart == -1)
{
if (boundSelectionEnd == 0)
{
selectionLength -= selectionEnd - captureStart;
}
else if (boundSelectionEnd == 1)
{
selectionLength -= captureLength;
}
}
else if (boundSelectionStart == 0)
{
if (boundSelectionEnd == 0)
{
selectionStart = captureStart;
selectionLength = 0;
}
else if (boundSelectionEnd == 1)
{
selectionStart = captureStart;
selectionLength -= captureEnd - selectionStart;
}
}
else if (boundSelectionStart == 1)
{
selectionStart -= captureLength;
}
leftShift++;
}
}
textBox.SelectionStart = selectionStart;
textBox.SelectionLength = selectionLength;
return matched;
}
How to process SIGTERM signal gracefully?
The simplest solution I have found, taking inspiration by responses above is
class SignalHandler:
def __init__(self):
# register signal handlers
signal.signal(signal.SIGINT, self.exit_gracefully)
signal.signal(signal.SIGTERM, self.exit_gracefully)
self.logger = Logger(level=ERROR)
def exit_gracefully(self, signum, frame):
self.logger.info('captured signal %d' % signum)
traceback.print_stack(frame)
###### do your resources clean up here! ####
raise(SystemExit)
Case Insensitive String comp in C
Additional pitfalls to watch out for when doing case insensitive compares:
Comparing as lower or as upper case? (common enough issue)
Both below will return 0 with strcicmpL("A", "a")
and strcicmpU("A", "a")
.
Yet strcicmpL("A", "_")
and strcicmpU("A", "_")
can return different signed results as '_'
is often between the upper and lower case letters.
This affects the sort order when used with qsort(..., ..., ..., strcicmp)
. Non-standard library C functions like the commonly available stricmp()
or strcasecmp()
tend to be well defined and favor comparing via lowercase. Yet variations exist.
int strcicmpL(char const *a, char const *b) {
while (*b) {
int d = tolower(*a) - tolower(*b);
if (d) {
return d;
}
a++;
b++;
}
return tolower(*a);
}
int strcicmpU(char const *a, char const *b) {
while (*b) {
int d = toupper(*a) - toupper(*b);
if (d) {
return d;
}
a++;
b++;
}
return toupper(*a);
}
char
can have a negative value. (not rare)
touppper(int)
and tolower(int)
are specified for unsigned char
values and the negative EOF
. Further, strcmp()
returns results as if each char
was converted to unsigned char
, regardless if char
is signed or unsigned.
tolower(*a); // Potential UB
tolower((unsigned char) *a); // Correct (Almost - see following)
char
can have a negative value and not 2's complement. (rare)
The above does not handle -0
nor other negative values properly as the bit pattern should be interpreted as unsigned char
. To properly handle all integer encodings, change the pointer type first.
// tolower((unsigned char) *a);
tolower(*(const unsigned char *)a); // Correct
Locale (less common)
Although character sets using ASCII code (0-127) are ubiquitous, the remainder codes tend to have locale specific issues. So strcasecmp("\xE4", "a")
might return a 0 on one system and non-zero on another.
Unicode (the way of the future)
If a solution needs to handle more than ASCII consider a unicode_strcicmp()
. As C lib does not provide such a function, a pre-coded function from some alternate library is recommended. Writing your own unicode_strcicmp()
is a daunting task.
Do all letters map one lower to one upper? (pedantic)
[A-Z] maps one-to-one with [a-z], yet various locales map various lower case chracters to one upper and visa-versa. Further, some uppercase characters may lack a lower case equivalent and again, visa-versa.
This obliges code to covert through both tolower()
and tolower()
.
int d = tolower(toupper(*a)) - tolower(toupper(*b));
Again, potential different results for sorting if code did tolower(toupper(*a))
vs. toupper(tolower(*a))
.
Portability
@B. Nadolson recommends to avoid rolling your own strcicmp()
and this is reasonable, except when code needs high equivalent portable functionality.
Below is an approach that even performed faster than some system provided functions. It does a single compare per loop rather than two by using 2 different tables that differ with '\0'
. Your results may vary.
static unsigned char low1[UCHAR_MAX + 1] = {
0, 1, 2, 3, ...
'@', 'a', 'b', 'c', ... 'z', `[`, ... // @ABC... Z[...
'`', 'a', 'b', 'c', ... 'z', `{`, ... // `abc... z{...
}
static unsigned char low2[UCHAR_MAX + 1] = {
// v--- Not zero, but A which matches none in `low1[]`
'A', 1, 2, 3, ...
'@', 'a', 'b', 'c', ... 'z', `[`, ...
'`', 'a', 'b', 'c', ... 'z', `{`, ...
}
int strcicmp_ch(char const *a, char const *b) {
// compare using tables that differ slightly.
while (low1[*(const unsigned char *)a] == low2[*(const unsigned char *)b]) {
a++;
b++;
}
// Either strings differ or null character detected.
// Perform subtraction using same table.
return (low1[*(const unsigned char *)a] - low1[*(const unsigned char *)b]);
}
Winforms TableLayoutPanel adding rows programmatically
I just looked into my code. In one application, I just add the controls, but without specifying the index, and when done, I just loop through the row styles and set the size type to AutoSize. So just adding them without specifying the indices seems to add the rows as intended (provided the GrowStyle is set to AddRows).
In another application, I clear the controls and set the RowCount property to the needed value. This does not add the RowStyles. Then I add my controls, this time specifying the indices, and add a new RowStyle (RowStyles.Add(new RowStyle(...)
) and this also works.
So, pick one of these methods, they both work. I remember the headaches the table layout panel caused me.
Freely convert between List<T> and IEnumerable<T>
A List<T>
is already an IEnumerable<T>
, so you can run LINQ statements directly on your List<T>
variable.
If you don't see the LINQ extension methods like OrderBy()
I'm guessing it's because you don't have a using System.Linq
directive in your source file.
You do need to convert the LINQ expression result back to a List<T>
explicitly, though:
List<Customer> list = ...
list = list.OrderBy(customer => customer.Name).ToList()
html tables & inline styles
This should do the trick:
<table width="400" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="50" height="40" valign="top" rowspan="3">
<img alt="" src="" width="40" height="40" style="margin: 0; border: 0; padding: 0; display: block;">
</td>
<td width="350" height="40" style="font-family: Helvetica, Arial, sans-serif; font-size: 14px; color: #000000;">
<a href="" style="color: #D31145; font-weight: bold; text-decoration: none;">LAST FIRST</a><br>
REALTOR | P 123.456.789
</td>
</tr>
<tr>
<td width="350" height="70" valign="bottom" style="font-family: Helvetica, Arial, sans-serif; font-size: 14px; color: #000000;">
<img alt="" src="" width="200" height="60" style="margin: 0; border: 0; padding: 0; display: block;">
</td>
</tr>
<tr>
<td width="350" height="20" valign="bottom" style="font-family: Helvetica, Arial, sans-serif; font-size: 10px; color: #000000;">
all your minor text here | all your minor text here | all your minor text here
</td>
</tr>
</table>
UPDATE: Adjusted code per the comments:
After viewing your jsFiddle, an important thing to note about tables is that table cell widths in each additional row all have to be the same width as the first, and all cells must add to the total width of your table.
Here is an example that will NOT WORK:
<table width="600" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="200" bgcolor="#252525">
</td>
<td width="400" bgcolor="#454545">
</td>
</tr>
<tr>
<td width="300" bgcolor="#252525">
</td>
<td width="300" bgcolor="#454545">
</td>
</tr>
</table>
Although the 2nd row does add up to 600, it (and any additional rows) must have the same 200-400 split as the first row, unless you are using colspans. If you use a colspan, you could have one row, but it needs to have the same width as the cells it is spanning, so this works:
<table width="600" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="200" bgcolor="#252525">
</td>
<td width="400" bgcolor="#454545">
</td>
</tr>
<tr>
<td width="600" colspan="2" bgcolor="#353535">
</td>
</tr>
</table>
Not a full tutorial, but I hope that helps steer you in the right direction in the future.
Here is the code you are after:
<table width="900" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="57" height="43" valign="top" rowspan="2">
<img alt="Rashel Adragna" src="http://zoparealtygroup.com/wp-content/uploads/2013/10/sig_head.png" width="47" height="43" style="margin: 0; border: 0; padding: 0; display: block;">
</td>
<td width="843" height="43" style="font-family: Helvetica, Arial, sans-serif; font-size: 14px; color: #000000;">
<a href="" style="color: #D31145; font-weight: bold; text-decoration: none;">RASHEL ADRAGNA</a><br>
REALTOR | P 855.900.24KW
</td>
</tr>
<tr>
<td width="843" height="64" valign="bottom" style="font-family: Helvetica, Arial, sans-serif; font-size: 14px; color: #000000;">
<img alt="Zopa Realty Group logo" src="http://zoparealtygroup.com/wp-content/uploads/2013/10/sig_logo.png" width="177" height="54" style="margin: 0; border: 0; padding: 0; display: block;">
</td>
</tr>
<tr>
<td width="843" colspan="2" height="20" valign="bottom" align="center" style="font-family: Helvetica, Arial, sans-serif; font-size: 10px; color: #000000;">
all your minor text here | all your minor text here | all your minor text here
</td>
</tr>
</table>
You'll note that I've added an extra 10px to some of your table cells. This in combination with align/valigns act as padding between your cells. It is a clever way to aviod actually having to add padding, margins or empty padding cells.
Clearing localStorage in javascript?
If you want to clear all item you stored in localStorage then
localStorage.clear();
Use this for clear all stored key.
If you want to clear/remove only specific key/value then you can use removeItem(key).
localStorage.removeItem('yourKey');
Inserting multiple rows in mysql
BEGIN;
INSERT INTO test_b (price_sum)
SELECT price
FROM test_a;
INSERT INTO test_c (price_summ)
SELECT price
FROM test_a;
COMMIT;
Real escape string and PDO
PDO offers an alternative designed to replace mysql_escape_string() with the PDO::quote() method.
Here is an excerpt from the PHP website:
<?php
$conn = new PDO('sqlite:/home/lynn/music.sql3');
/* Simple string */
$string = 'Nice';
print "Unquoted string: $string\n";
print "Quoted string: " . $conn->quote($string) . "\n";
?>
The above code will output:
Unquoted string: Nice
Quoted string: 'Nice'
Python Pandas merge only certain columns
You want to use TWO brackets, so if you are doing a VLOOKUP sort of action:
df = pd.merge(df,df2[['Key_Column','Target_Column']],on='Key_Column', how='left')
This will give you everything in the original df + add that one corresponding column in df2 that you want to join.
Creating the Singleton design pattern in PHP5
Supports Multiple Objects with 1 line per class:
This method will enforce singletons on any class you wish, al you have to do is add 1 method to the class you wish to make a singleton and this will do it for you.
This also stores objects in a "SingleTonBase" class so you can debug all your objects that you have used in your system by recursing the SingleTonBase
objects.
Create a file called SingletonBase.php and include it in root of your script!
The code is
abstract class SingletonBase
{
private static $storage = array();
public static function Singleton($class)
{
if(in_array($class,self::$storage))
{
return self::$storage[$class];
}
return self::$storage[$class] = new $class();
}
public static function storage()
{
return self::$storage;
}
}
Then for any class you want to make a singleton just add this small single method.
public static function Singleton()
{
return SingletonBase::Singleton(get_class());
}
Here is a small example:
include 'libraries/SingletonBase.resource.php';
class Database
{
//Add that singleton function.
public static function Singleton()
{
return SingletonBase::Singleton(get_class());
}
public function run()
{
echo 'running...';
}
}
$Database = Database::Singleton();
$Database->run();
And you can just add this singleton function in any class you have and it will only create 1 instance per class.
NOTE: You should always make the __construct private to eliminate the use of new Class(); instantiations.
When use ResponseEntity<T> and @RestController for Spring RESTful applications
To complete the answer from Sotorios Delimanolis.
It's true that ResponseEntity
gives you more flexibility but in most cases you won't need it and you'll end up with these ResponseEntity
everywhere in your controller thus making it difficult to read and understand.
If you want to handle special cases like errors (Not Found, Conflict, etc.), you can add a HandlerExceptionResolver
to your Spring configuration. So in your code, you just throw a specific exception (NotFoundException
for instance) and decide what to do in your Handler (setting the HTTP status to 404), making the Controller code more clear.
How to convert an integer to a string in any base?
Great answers!
I guess the answer to my question was "no" I was not missing some obvious solution.
Here is the function I will use that condenses the good ideas expressed in the answers.
- allow caller-supplied mapping of characters (allows base64 encode)
- checks for negative and zero
- maps complex numbers into tuples of strings
def int2base(x,b,alphabet='0123456789abcdefghijklmnopqrstuvwxyz'):
'convert an integer to its string representation in a given base'
if b<2 or b>len(alphabet):
if b==64: # assume base64 rather than raise error
alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
else:
raise AssertionError("int2base base out of range")
if isinstance(x,complex): # return a tuple
return ( int2base(x.real,b,alphabet) , int2base(x.imag,b,alphabet) )
if x<=0:
if x==0:
return alphabet[0]
else:
return '-' + int2base(-x,b,alphabet)
# else x is non-negative real
rets=''
while x>0:
x,idx = divmod(x,b)
rets = alphabet[idx] + rets
return rets
How to split a string to 2 strings in C
This is how you implement a strtok()
like function (taken from a BSD licensed string processing library for C, called zString).
Below function differs from the standard strtok()
in the way it recognizes consecutive delimiters, whereas the standard strtok()
does not.
char *zstring_strtok(char *str, const char *delim) {
static char *static_str=0; /* var to store last address */
int index=0, strlength=0; /* integers for indexes */
int found = 0; /* check if delim is found */
/* delimiter cannot be NULL
* if no more char left, return NULL as well
*/
if (delim==0 || (str == 0 && static_str == 0))
return 0;
if (str == 0)
str = static_str;
/* get length of string */
while(str[strlength])
strlength++;
/* find the first occurance of delim */
for (index=0;index<strlength;index++)
if (str[index]==delim[0]) {
found=1;
break;
}
/* if delim is not contained in str, return str */
if (!found) {
static_str = 0;
return str;
}
/* check for consecutive delimiters
*if first char is delim, return delim
*/
if (str[0]==delim[0]) {
static_str = (str + 1);
return (char *)delim;
}
/* terminate the string
* this assignmetn requires char[], so str has to
* be char[] rather than *char
*/
str[index] = '\0';
/* save the rest of the string */
if ((str + index + 1)!=0)
static_str = (str + index + 1);
else
static_str = 0;
return str;
}
Below is an example code that demonstrates the usage
Example Usage
char str[] = "A,B,,,C";
printf("1 %s\n",zstring_strtok(s,","));
printf("2 %s\n",zstring_strtok(NULL,","));
printf("3 %s\n",zstring_strtok(NULL,","));
printf("4 %s\n",zstring_strtok(NULL,","));
printf("5 %s\n",zstring_strtok(NULL,","));
printf("6 %s\n",zstring_strtok(NULL,","));
Example Output
1 A
2 B
3 ,
4 ,
5 C
6 (null)
You can even use a while loop (standard library's strtok()
would give the same result here)
char s[]="some text here;
do {
printf("%s\n",zstring_strtok(s," "));
} while(zstring_strtok(NULL," "));
Python Array with String Indices
Even better, try an OrderedDict (assuming you want something like a list). Closer to a list than a regular dict since the keys have an order just like list elements have an order. With a regular dict, the keys have an arbitrary order.
Note that this is available in Python 3 and 2.7. If you want to use with an earlier version of Python you can find installable modules to do that.
Downloading a picture via urllib and python
Maybe you need 'User-Agent':
import urllib2
opener = urllib2.build_opener()
opener.addheaders = [('User-Agent', 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.137 Safari/537.36')]
response = opener.open('http://google.com')
htmlData = response.read()
f = open('file.txt','w')
f.write(htmlData )
f.close()
How do I get the directory that a program is running from?
Path to the current .exe
#include <Windows.h>
std::wstring getexepathW()
{
wchar_t result[MAX_PATH];
return std::wstring(result, GetModuleFileNameW(NULL, result, MAX_PATH));
}
std::wcout << getexepathW() << std::endl;
// -------- OR --------
std::string getexepathA()
{
char result[MAX_PATH];
return std::string(result, GetModuleFileNameA(NULL, result, MAX_PATH));
}
std::cout << getexepathA() << std::endl;
Disable cross domain web security in Firefox
For anyone finding this question while using Nightwatch.js (1.3.4), there's an acceptInsecureCerts: true
setting in the config file:
_x000D_
_x000D_
firefox: {_x000D_
desiredCapabilities: {_x000D_
browserName: 'firefox',_x000D_
alwaysMatch: {_x000D_
// Enable this if you encounter unexpected SSL certificate errors in Firefox_x000D_
acceptInsecureCerts: true,_x000D_
'moz:firefoxOptions': {_x000D_
args: [_x000D_
// '-headless',_x000D_
// '-verbose'_x000D_
],_x000D_
}_x000D_
}_x000D_
}_x000D_
},
_x000D_
_x000D_
_x000D_
Bad Request - Invalid Hostname IIS7
This solved my problem (sorry for my bad English):
open cmd as administrator and run command (Without the square brackets):
netsh http add urlacl url=http://[ip adress]:[port]/ user=everyone
in documents/iisexpress/config/applicationhost.config
and in your root project folder in (hidden) folder: .vs/config/applicationhost.config
you need add row to "site" tag:
<binding protocol="http" bindingInformation="*:8080:192.xxx.xxx.xxx" />
open "internet information services (iis) manager"
(to find it: in search in taskbar write "Turn Window features on or off" and open result and then check the checkbox "internet information service" and install that):
- in left screen click: computer-name --> Sites --> Default Web Site and
- then click in right screen "Binding"
- click Add button
- write what you need and press "OK".
open "Windows Firewall With Advanced Security",
- in left screen press "Inbound Rules" and then
- press in right screen "New Rule..."
- check port and press Next,
- check TCP and your port and press Next,
- check "Allow the connection" and press Next,
- check all checkbox and press Next,
- write name and press Finish.
done.
Why do we assign a parent reference to the child object in Java?
for example we have a
class Employee
{
int getsalary()
{return 0;}
String getDesignation()
{
return “default”;
}
}
class Manager extends Employee
{
int getsalary()
{
return 20000;
}
String getDesignation()
{
return “Manager”
}
}
class SoftwareEngineer extends Employee
{
int getsalary()
{
return 20000;
}
String getDesignation()
{
return “Manager”
}
}
now if you want to set or get salary and designation of all employee (i.e software enginerr,manager etc )
we will take an array of Employee and call both method getsalary(),getDesignation
Employee arr[]=new Employee[10];
arr[1]=new SoftwareEngieneer();
arr[2]=new Manager();
arr[n]=…….
for(int i;i>arr.length;i++)
{
System.out.println(arr[i].getDesignation+””+arr[i].getSalary())
}
now its an kind of loose coupling because you can have different types of employees ex:softeware engineer,manager,hr,pantryEmployee etc
so you can give object to the parent reference irrespective of different employee object
How can I insert multiple rows into oracle with a sequence value?
It does not work because sequence does not work in following scenarios:
- In a WHERE clause
- In a GROUP BY or ORDER BY clause
- In a DISTINCT clause
- Along with a UNION or INTERSECT or MINUS
- In a sub-query
Source: http://www.orafaq.com/wiki/ORA-02287
However this does work:
insert into table_name
(col1, col2)
select my_seq.nextval, inner_view.*
from (select 'some value' someval
from dual
union all
select 'another value' someval
from dual) inner_view;
Try it out:
create table table_name(col1 varchar2(100), col2 varchar2(100));
create sequence vcert.my_seq
start with 1
increment by 1
minvalue 0;
select * from table_name;
Azure SQL Database "DTU percentage" metric
A DTU is a unit of measure for the performance of a service tier and is a summary of several database characteristics. Each service tier has a certain number of DTUs assigned to it as an easy way to compare the performance level of one tier versus another.
Database Throughput Unit (DTU): DTUs provide a way to
describe the relative capacity of a performance level of Basic,
Standard, and Premium databases. DTUs are based on a blended measure
of CPU, memory, reads, and writes. As DTUs increase, the power offered
by the performance level increases. For example, a performance level
with 5 DTUs has five times more power than a performance level with 1
DTU. A maximum DTU quota applies to each server.
The DTU Quota applies to the server, not the individual databases and each server has a maximum of 1600 DTUs. The DTU% is the percentage of units your particular database is using and it seems that this number can go over 100% of the DTU rating of the service tier (I assume to the limit of the server). This percentage number is designed to help you choose the appropriate service tier.
From down toward the bottom of this announcement:
For example, if your DTU consumption shows a value of 80%, it
indicates it is consuming DTU at the rate of 80% of the limit an S2
database would have. If you see values greater than 100% in this view
it means that you need a performance tier larger than S2.
As an example, let’s say you see a percentage value of 300%. This
tells you that you are using three times more resources than would be
available in an S2. To determine a reasonable starting size, compare
the DTUs available in an S2 (50 DTUs) with the next higher sizes (P1 =
100 DTUs, or 200% of S2, P2 = 200 DTUs or 400% of S2). Because you
are at 300% of S2 you would want to start with a P2 and re-test.
Remove multiple objects with rm()
Another variation you can try is(expanding @mnel's answer)
if you have many temp'x'.
here "n" could be the number of temp variables present
rm(list = c(paste("temp",c(1:n),sep="")))
How to do constructor chaining in C#
I hope following example shed some light on constructor chaining.
my use case here for example, you are expecting user to pass a directory to your
constructor, user doesn't know what directory to pass and decides to let
you assign default directory. you step up and assign a default directory that you think
will work.
BTW, I used LINQPad for this example in case you are wondering what *.Dump() is.
cheers
void Main()
{
CtorChaining ctorNoparam = new CtorChaining();
ctorNoparam.Dump();
//Result --> BaseDir C:\Program Files (x86)\Default\
CtorChaining ctorOneparam = new CtorChaining("c:\\customDir");
ctorOneparam.Dump();
//Result --> BaseDir c:\customDir
}
public class CtorChaining
{
public string BaseDir;
public static string DefaultDir = @"C:\Program Files (x86)\Default\";
public CtorChaining(): this(null) {}
public CtorChaining(string baseDir): this(baseDir, DefaultDir){}
public CtorChaining(string baseDir, string defaultDir)
{
//if baseDir == null, this.BaseDir = @"C:\Program Files (x86)\Default\"
this.BaseDir = baseDir ?? defaultDir;
}
}
Function for C++ struct
Yes, a struct
is identical to a class
except for the default access level (member-wise and inheritance-wise). (and the extra meaning class
carries when used with a template)
Every functionality supported by a class is consequently supported by a struct. You'd use methods the same as you'd use them for a class.
struct foo {
int bar;
foo() : bar(3) {} //look, a constructor
int getBar()
{
return bar;
}
};
foo f;
int y = f.getBar(); // y is 3
Can linux cat command be used for writing text to file?
The Solution to your problem is :
echo " Some Text Goes Here " > filename.txt
But you can use cat command if you want to redirect the output of a file to some other file or if you want to append the output of a file to another file :
cat filename > newfile -- To redirect output of filename to newfile
cat filename >> newfile -- To append the output of filename to newfile
Simplest way to detect keypresses in javascript
With plain Javascript, the simplest is:
document.onkeypress = function (e) {
e = e || window.event;
// use e.keyCode
};
But with this, you can only bind one handler for the event.
In addition, you could use the following to be able to potentially bind multiple handlers to the same event:
addEvent(document, "keypress", function (e) {
e = e || window.event;
// use e.keyCode
});
function addEvent(element, eventName, callback) {
if (element.addEventListener) {
element.addEventListener(eventName, callback, false);
} else if (element.attachEvent) {
element.attachEvent("on" + eventName, callback);
} else {
element["on" + eventName] = callback;
}
}
In either case, keyCode
isn't consistent across browsers, so there's more to check for and figure out. Notice the e = e || window.event
- that's a normal problem with Internet Explorer, putting the event in window.event
instead of passing it to the callback.
References:
With jQuery:
$(document).on("keypress", function (e) {
// use e.which
});
Reference:
Other than jQuery being a "large" library, jQuery really helps with inconsistencies between browsers, especially with window events...and that can't be denied. Hopefully it's obvious that the jQuery code I provided for your example is much more elegant and shorter, yet accomplishes what you want in a consistent way. You should be able to trust that e
(the event) and e.which
(the key code, for knowing which key was pressed) are accurate. In plain Javascript, it's a little harder to know unless you do everything that the jQuery library internally does.
Note there is a keydown
event, that is different than keypress
. You can learn more about them here: onKeyPress Vs. onKeyUp and onKeyDown
As for suggesting what to use, I would definitely suggest using jQuery if you're up for learning the framework. At the same time, I would say that you should learn Javascript's syntax, methods, features, and how to interact with the DOM. Once you understand how it works and what's happening, you should be more comfortable working with jQuery. To me, jQuery makes things more consistent and is more concise. In the end, it's Javascript, and wraps the language.
Another example of jQuery being very useful is with AJAX. Browsers are inconsistent with how AJAX requests are handled, so jQuery abstracts that so you don't have to worry.
Here's something that might help decide:
Python: Assign Value if None Exists
You should initialize variables to None and then check it:
var1 = None
if var1 is None:
var1 = 4
Which can be written in one line as:
var1 = 4 if var1 is None else var1
or using shortcut (but checking against None is recommended)
var1 = var1 or 4
alternatively if you will not have anything assigned to variable that variable name doesn't exist and hence using that later will raise NameError
, and you can also use that knowledge to do something like this
try:
var1
except NameError:
var1 = 4
but I would advise against that.
How to add anything in <head> through jquery/javascript?
You can use innerHTML
to just concat the extra field string;
document.head.innerHTML = document.head.innerHTML + '<link rel="stylesheet>...'
However, you can't guarantee that the extra things you add to the head will be recognised by the browser after the first load, and it's possible you will get a FOUC (flash of unstyled content) as the extra stylesheets are loaded.
I haven't looked at the API in years, but you could also use document.write
, which is what was designed for this sort of action. However, this would require you to block the page from rendering until your initial AJAX request has completed.
Recursively list files in Java
My version (of course I could have used the built in walk in Java 8 ;-) ):
public static List<File> findFilesIn(File rootDir, Predicate<File> predicate) {
ArrayList<File> collected = new ArrayList<>();
walk(rootDir, predicate, collected);
return collected;
}
private static void walk(File dir, Predicate<File> filterFunction, List<File> collected) {
Stream.of(listOnlyWhenDirectory(dir))
.forEach(file -> walk(file, filterFunction, addAndReturn(collected, file, filterFunction)));
}
private static File[] listOnlyWhenDirectory(File dir) {
return dir.isDirectory() ? dir.listFiles() : new File[]{};
}
private static List<File> addAndReturn(List<File> files, File toAdd, Predicate<File> filterFunction) {
if (filterFunction.test(toAdd)) {
files.add(toAdd);
}
return files;
}
MySQL join with where clause
You need to put it in the join
clause, not the where
:
SELECT *
FROM categories
LEFT JOIN user_category_subscriptions ON
user_category_subscriptions.category_id = categories.category_id
and user_category_subscriptions.user_id =1
See, with an inner join
, putting a clause in the join
or the where
is equivalent. However, with an outer join
, they are vastly different.
As a join
condition, you specify the rowset that you will be joining to the table. This means that it evaluates user_id = 1
first, and takes the subset of user_category_subscriptions
with a user_id
of 1
to join to all of the rows in categories
. This will give you all of the rows in categories
, while only the categories
that this particular user has subscribed to will have any information in the user_category_subscriptions
columns. Of course, all other categories
will be populated with null
in the user_category_subscriptions
columns.
Conversely, a where
clause does the join, and then reduces the rowset. So, this does all of the joins and then eliminates all rows where user_id
doesn't equal 1
. You're left with an inefficient way to get an inner join
.
Hopefully this helps!
Android: remove notification from notification bar
On Android API >=23 you can do somehting like this to remove a group of notifications.
for (StatusBarNotification statusBarNotification : mNotificationManager.getActiveNotifications()) {
if (KEY_MESSAGE_GROUP.equals(statusBarNotification.getGroupKey())) {
mNotificationManager.cancel(statusBarNotification.getId());
}
}
PHP json_encode encoding numbers as strings
So Pascal MARTIN isn't getting enough credit here. Checking for numeric values on every JSON return is not feasable for an existing project with hundreds of server side functions.
I replaced php-mysql with php-mysqlnd, and the problem went away. Numbers are numbers, strings are strings, booleans are boolean.
Get table column names in MySQL?
It's also interesting to note that you can use
EXPLAIN table_name
which is synonymous with DESCRIBE table_name
and SHOW COLUMNS FROM table_name
although EXPLAIN is more commonly used to obtain information about the query execution plan.
How to detect my browser version and operating system using JavaScript?
To get the new Microsoft Edge based on a Mozilla core add:
else if ((verOffset=nAgt.indexOf("Edg"))!=-1) {
browserName = "Microsoft Edge";
fullVersion = nAgt.substring(verOffset+5);
}
before
// In Chrome, the true version is after "Chrome"
else if ((verOffset=nAgt.indexOf("Chrome"))!=-1) {
browserName = "Chrome";
fullVersion = nAgt.substring(verOffset+7);
}
Find value in an array
If you want find one value from array, use Array#find
:
arr = [1,2,6,4,9]
arr.find {|e| e % 3 == 0} #=> 6
See also:
arr.select {|e| e % 3 == 0} #=> [ 6, 9 ]
e.include? 6 #=> true
To find if a value exists in an Array you can also use #in?
when using ActiveSupport. #in?
works for any object that responds to #include?
:
arr = [1, 6]
6.in? arr #=> true
How to enable loglevel debug on Apache2 server
Do note that on newer Apache versions the RewriteLog
and RewriteLogLevel
have been removed, and in fact will now trigger an error when trying to start Apache (at least on my XAMPP installation with Apache 2.4.2):
AH00526: Syntax error on line xx of path/to/config/file.conf:
Invalid command 'RewriteLog', perhaps misspelled or defined by a module not included in the server configuration`
Instead, you're now supposed to use the general LogLevel
directive, with a level of trace1
up to trace8
. 'debug' didn't display any rewrite messages in the log for me.
Example: LogLevel warn rewrite:trace3
For the official documentation, see here.
Of course this also means that now your rewrite logs will be written in the general error log file and you'll have to sort them out yourself.
What is inf and nan?
You say:
when i do nan - inf
i dont get -inf
i get nan
This is because any operation containing NaN
as an operand would return NaN
.
A comparison with NaN
would return an unordered result.
>>> float('Inf') == float('Inf')
True
>>> float('NaN') == float('NaN')
False
How to calculate growth with a positive and negative number?
Simplest solution is the following:
=(NEW/OLD-1)*SIGN(OLD)
The SIGN()
function will result in -1
if the value is negative and 1
if the value is positive. So multiplying by that will conditionally invert the result if the previous value is negative.
TypeScript error TS1005: ';' expected (II)
The issue was in my code.
In large code base, issue was not clear.
A simplified code is below:
Bad:
collection.insertMany(
[[],
function (err, result) {
});
Good:
collection.insertMany(
[],
function (err, result) {
});
That is, the first one has [[], instead of normal array []
TS error was not clear enough, and it showed error in the last line with });
Hope this helps.
Redirect in Spring MVC
try to change this in your dispatcher-servlet.xml
<!-- Your View Resolver -->
<bean id="viewResolver" class="org.springframework.web.servlet.view.ResourceBundleViewResolver">
<property name="basenames" value="views" />
<property name="order" value="1" />
</bean>
<!-- UrlBasedViewResolver to Handle Redirects & Forward -->
<bean id="urlViewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver">
<property name="viewClass" value="org.springframework.web.servlet.view.tiles2.TilesView" />
<property name="order" value="2" />
</bean>
What happens is clearly explained here http://projects.nigelsim.org/wiki/RedirectWithSpringWebMvc
Centos/Linux setting logrotate to maximum file size for all logs
It specifies the size of the log file to trigger rotation. For example size 50M
will trigger a log rotation once the file is 50MB or greater in size. You can use the suffix M
for megabytes, k
for kilobytes, and G
for gigabytes. If no suffix is used, it will take it to mean bytes. You can check the example at the end. There are three directives available size
, maxsize
, and minsize
. According to manpage:
minsize size
Log files are rotated when they grow bigger than size bytes,
but not before the additionally specified time interval (daily,
weekly, monthly, or yearly). The related size option is simi-
lar except that it is mutually exclusive with the time interval
options, and it causes log files to be rotated without regard
for the last rotation time. When minsize is used, both the
size and timestamp of a log file are considered.
size size
Log files are rotated only if they grow bigger then size bytes.
If size is followed by k, the size is assumed to be in kilo-
bytes. If the M is used, the size is in megabytes, and if G is
used, the size is in gigabytes. So size 100, size 100k, size
100M and size 100G are all valid.
maxsize size
Log files are rotated when they grow bigger than size bytes even before
the additionally specified time interval (daily, weekly, monthly,
or yearly). The related size option is similar except that it
is mutually exclusive with the time interval options, and it causes
log files to be rotated without regard for the last rotation time.
When maxsize is used, both the size and timestamp of a log file are
considered.
Here is an example:
"/var/log/httpd/access.log" /var/log/httpd/error.log {
rotate 5
mail [email protected]
size 100k
sharedscripts
postrotate
/usr/bin/killall -HUP httpd
endscript
}
Here is an explanation for both files /var/log/httpd/access.log
and /var/log/httpd/error.log
. They are rotated whenever it grows over 100k in size, and the old logs files are mailed (uncompressed) to [email protected]
after going through 5 rotations, rather than being removed. The sharedscripts
means that the postrotate
script will only be run once (after the old logs have been compressed), not once for each log which is rotated. Note that the double quotes around the first filename at the beginning of this section allows logrotate to rotate logs with spaces in the name. Normal shell quoting rules apply, with ,
, and \
characters supported.
Map vs Object in JavaScript
The key difference is that Objects only support string and Symbol keys where as Maps support more or less any key type.
If I do obj[123] = true
and then Object.keys(obj)
then I will get ["123"]
rather than [123]
. A Map would preserve the type of the key and return [123]
which is great. Maps also allow you to use Objects as keys. Traditionally to do this you would have to give objects some kind of unique identifier to hash them (I don't think I've ever seen anything like getObjectId
in JS as part of the standard). Maps also guarantee preservation of order so are all round better for preservation and can sometimes save you needing to do a few sorts.
Between maps and objects in practice there are several pros and cons. Objects gain both advantages and disadvantages being very tightly integrated into the core of JavaScript which sets them apart from significantly Map beyond the difference in key support.
An immediate advantage is that you have syntactical support for Objects making it easy to access elements. You also have direct support for it with JSON. When used as a hash it's annoying to get an object without any properties at all. By default if you want to use Objects as a hash table they will be polluted and you will often have to call hasOwnProperty
on them when accessing properties. You can see here how by default Objects are polluted and how to create hopefully unpolluted objects for use as hashes:
({}).toString
toString() { [native code] }
JSON.parse('{}').toString
toString() { [native code] }
(Object.create(null)).toString
undefined
JSON.parse('{}', (k,v) => (typeof v === 'object' && Object.setPrototypeOf(v, null) ,v)).toString
undefined
Pollution on objects is not only something that makes code more annoying, slower, etc but can also have potential consequences for security.
Objects are not pure hash tables but are trying to do more. You have headaches like hasOwnProperty
, not being able to get the length easily (Object.keys(obj).length
) and so on. Objects are not meant to purely be used as hash maps but as dynamic extensible Objects as well and so when you use them as pure hash tables problems arise.
Comparison/List of various common operations:
Object:
var o = {};
var o = Object.create(null);
o.key = 1;
o.key += 10;
for(let k in o) o[k]++;
var sum = 0;
for(let v of Object.values(m)) sum += v;
if('key' in o);
if(o.hasOwnProperty('key'));
delete(o.key);
Object.keys(o).length
Map:
var m = new Map();
m.set('key', 1);
m.set('key', m.get('key') + 10);
m.foreach((k, v) => m.set(k, m.get(k) + 1));
for(let k of m.keys()) m.set(k, m.get(k) + 1);
var sum = 0;
for(let v of m.values()) sum += v;
if(m.has('key'));
m.delete('key');
m.size();
There are a few other options, approaches, methodologies, etc with varying ups and downs (performance, terse, portable, extendable, etc). Objects are a bit strange being core to the language so you have a lot of static methods for working with them.
Besides the advantage of Maps preserving key types as well as being able to support things like objects as keys they are isolated from the side effects that objects much have. A Map is a pure hash, there's no confusion about trying to be an object at the same time. Maps can also be easily extended with proxy functions. Object's currently have a Proxy class however performance and memory usage is grim, in fact creating your own proxy that looks like Map for Objects currently performs better than Proxy.
A substantial disadvantage for Maps is that they are not supported with JSON directly. Parsing is possible but has several hangups:
JSON.parse(str, (k,v) => {
if(typeof v !== 'object') return v;
let m = new Map();
for(k in v) m.set(k, v[k]);
return m;
});
The above will introduce a serious performance hit and will also not support any string keys. JSON encoding is even more difficult and problematic (this is one of many approaches):
// An alternative to this it to use a replacer in JSON.stringify.
Map.prototype.toJSON = function() {
return JSON.stringify({
keys: Array.from(this.keys()),
values: Array.from(this.values())
});
};
This is not so bad if you're purely using Maps but will have problems when you are mixing types or using non-scalar values as keys (not that JSON is perfect with that kind of issue as it is, IE circular object reference). I haven't tested it but chances are that it will severely hurt performance compared to stringify.
Other scripting languages often don't have such problems as they have explicit non-scalar types for Map, Object and Array. Web development is often a pain with non-scalar types where you have to deal with things like PHP merges Array/Map with Object using A/M for properties and JS merges Map/Object with Array extending M/O. Merging complex types is the devil's bane of high level scripting languages.
So far these are largely issues around implementation but performance for basic operations is important as well. Performance is also complex because it depends on engine and usage. Take my tests with a grain of salt as I cannot rule out any mistake (I have to rush this). You should also run your own tests to confirm as mine examine only very specific simple scenarios to give a rough indication only. According to tests in Chrome for very large objects/maps the performance for objects is worse because of delete which is apparently somehow proportionate to the number of keys rather than O(1):
Object Set Took: 146
Object Update Took: 7
Object Get Took: 4
Object Delete Took: 8239
Map Set Took: 80
Map Update Took: 51
Map Get Took: 40
Map Delete Took: 2
Chrome clearly has a strong advantage with getting and updating but the delete performance is horrific. Maps use a tiny amount more memory in this case (overhead) but with only one Object/Map being tested with millions of keys the impact of overhead for maps is not expressed well. With memory management objects also do seem to free earlier if I am reading the profile correctly which might be one benefit in favor of objects.
In Firefox for this particular benchmark it is a different story:
Object Set Took: 435
Object Update Took: 126
Object Get Took: 50
Object Delete Took: 2
Map Set Took: 63
Map Update Took: 59
Map Get Took: 33
Map Delete Took: 1
I should immediately point out that in this particular benchmark deleting from objects in Firefox is not causing any problems, however in other benchmarks it has caused problems especially when there are many keys just as in Chrome. Maps are clearly superior in Firefox for large collections.
However this is not the end of the story, what about many small objects or maps? I have done a quick benchmark of this but not an exhaustive one (setting/getting) of which performs best with a small number of keys in the above operations. This test is more about memory and initialization.
Map Create: 69 // new Map
Object Create: 34 // {}
Again these figures vary but basically Object has a good lead. In some cases the lead for Objects over maps is extreme (~10 times better) but on average it was around 2-3 times better. It seems extreme performance spikes can work both ways. I only tested this in Chrome and creation to profile memory usage and overhead. I was quite surprised to see that in Chrome it appears that Maps with one key use around 30 times more memory than Objects with one key.
For testing many small objects with all the above operations (4 keys):
Chrome Object Took: 61
Chrome Map Took: 67
Firefox Object Took: 54
Firefox Map Took: 139
In terms of memory allocation these behaved the same in terms of freeing/GC but Map used 5 times more memory. This test used 4 keys where as in the last test I only set one key so this would explain the reduction in memory overhead. I ran this test a few times and Map/Object are more or less neck and neck overall for Chrome in terms of overall speed. In Firefox for small Objects there is a definite performance advantage over maps overall.
This of course doesn't include the individual options which could vary wildly. I would not advice micro-optimizing with these figures. What you can get out of this is that as a rule of thumb, consider Maps more strongly for very large key value stores and objects for small key value stores.
Beyond that the best strategy with these two it to implement it and just make it work first. When profiling it is important to keep in mind that sometimes things that you wouldn't think would be slow when looking at them can be incredibly slow because of engine quirks as seen with the object key deletion case.
Capitalize words in string
http://www.mediacollege.com/internet/javascript/text/case-capitalize.html is one of many answers out there.
Google can be all you need for such problems.
A naïve approach would be to split the string by whitespace, capitalize the first letter of each element of the resulting array and join it back together. This leaves existing capitalization alone (e.g. HTML stays HTML and doesn't become something silly like Html). If you don't want that affect, turn the entire string into lowercase before splitting it up.
Scanner vs. BufferedReader
Following are the differences between BufferedReader and Scanner
- BufferedReader only read data but scanner also parse data.
- you can only read String using BufferedReader, but you can read int,
long or float using Scanner.
- BufferedReader is older from Scanner,it exists from jdk 1.1 while
Scanner was added on JDK 5 release.
- The Buffer size of BufferedReader is large(8KB) as compared to 1KB
of Scanner.
- BufferedReader is more suitable for reading file with long String
while Scanner is more suitable for reading small user input from
command prompt.
- BufferedReader is synchronized but Scanner is not, which means you
cannot share Scanner among multiple threads.
- BufferedReader is faster than Scanner because it doesn't spent time
on parsing
- BufferedReader is a bit faster as compared to Scanner
- BufferedReader is from java.io package and Scanner is from java.util package
on basis of the points we can select our choice.
Thanks
get current url in twig template?
{{ path(app.request.attributes.get('_route'),
app.request.attributes.get('_route_params')) }}
If you want to read it into a view variable:
{% set currentPath = path(app.request.attributes.get('_route'),
app.request.attributes.get('_route_params')) %}
The app
global view variable contains all sorts of useful shortcuts, such as app.session
and app.security.token.user
, that reference the services you might use in a controller.
Changing navigation title programmatically
If you wanted to change the title from a child view controller of a Page View Controller that's embedded in a navigation controller, it would look like this:
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.parent?.title = "some title"
}
Allow a div to cover the whole page instead of the area within the container
Apply a css-reset to reset all the margins and paddings
like this
/* http://meyerweb.com/eric/tools/css/reset/
v2.0 | 20110126
License: none (public domain)
*/
html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed,
figure, figcaption, footer, header, hgroup,
menu, nav, output, ruby, section, summary,
time, mark, audio, video {
margin: 0;
padding: 0;
border: 0;
font-size: 100%;
font: inherit;
vertical-align: baseline;
}
/* HTML5 display-role reset for older browsers */
article, aside, details, figcaption, figure,
footer, header, hgroup, menu, nav, section {
display: block;
}
body {
line-height: 1;
}
ol, ul {
list-style: none;
}
blockquote, q {
quotes: none;
}
blockquote:before, blockquote:after,
q:before, q:after {
content: '';
content: none;
}
table {
border-collapse: collapse;
border-spacing: 0;
}
You can use various css-resets as you need, normal and use in css
html
{
margin: 0px;
padding: 0px;
}
body
{
margin: 0px;
padding: 0px;
}
HTML checkbox - allow to check only one checkbox
$(function () {
$('input[type=checkbox]').click(function () {
var chks = document.getElementById('<%= chkRoleInTransaction.ClientID %>').getElementsByTagName('INPUT');
for (i = 0; i < chks.length; i++) {
chks[i].checked = false;
}
if (chks.length > 1)
$(this)[0].checked = true;
});
});
What is newline character -- '\n'
NewLine (\n) is 10 (0xA) and CarriageReturn (\r) is 13 (0xD).
Different operating systems picked different end of line representations for files. Windows uses CRLF (\r\n). Unix uses LF (\n). Older Mac OS versions use CR (\r), but OS X switched to the Unix character.
Here is a relatively useful FAQ.
Aborting a shell script if any command returns a non-zero value
The if statements in your example are unnecessary. Just do it like this:
dosomething1 || exit 1
If you take Ville Laurikari's advice and use set -e
then for some commands you may need to use this:
dosomething || true
The || true
will make the command pipeline have a true
return value even if the command fails so the the -e
option will not kill the script.
android.os.NetworkOnMainThreadException with android 4.2
Please make sure that you don't do any network access on UI Thread, instead do it in Async Task
The reason why your application crashes on Android versions 3.0 and above, but works fine on Android 2.x is because since HoneyComb are much stricter about abuse against the UI Thread. For example, when an Android device running HoneyComb or above detects a network access on the UI thread, a NetworkOnMainThreadException will be thrown.
See this
Correct way to add external jars (lib/*.jar) to an IntelliJ IDEA project
If you are building your project with gradle, you just need to add one line to the dependencies in the build.gradle:
buildscript {
...
}
...
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
}
and then add the folder to your root project or module:
Then you drop your jars in there and you are good to go :-)
Where do I find the current C or C++ standard documents?
ISO standards cost money, from a moderate amount (for a PDF version), to a bit more (for a book version).
While they aren't finalised however, they can usually be found online, as drafts. Most of the times the final version doesn't differ significantly from the last draft, so while not perfect, they'll suit just fine.
round up to 2 decimal places in java?
Try :
class round{
public static void main(String args[]){
double a = 123.13698;
double roundOff = Math.round(a*100)/100;
String.format("%.3f", roundOff); //%.3f defines decimal precision you want
System.out.println(roundOff); }}
Getting list of tables, and fields in each, in a database
Is this what you are looking for:
Using OBJECT CATALOG VIEWS
SELECT T.name AS Table_Name ,
C.name AS Column_Name ,
P.name AS Data_Type ,
P.max_length AS Size ,
CAST(P.precision AS VARCHAR) + '/' + CAST(P.scale AS VARCHAR) AS Precision_Scale
FROM sys.objects AS T
JOIN sys.columns AS C ON T.object_id = C.object_id
JOIN sys.types AS P ON C.system_type_id = P.system_type_id
WHERE T.type_desc = 'USER_TABLE';
Using INFORMATION SCHEMA VIEWS
SELECT TABLE_SCHEMA ,
TABLE_NAME ,
COLUMN_NAME ,
ORDINAL_POSITION ,
COLUMN_DEFAULT ,
DATA_TYPE ,
CHARACTER_MAXIMUM_LENGTH ,
NUMERIC_PRECISION ,
NUMERIC_PRECISION_RADIX ,
NUMERIC_SCALE ,
DATETIME_PRECISION
FROM INFORMATION_SCHEMA.COLUMNS;
Reference : My Blog - http://dbalink.wordpress.com/2008/10/24/querying-the-object-catalog-and-information-schema-views/
@property retain, assign, copy, nonatomic in Objective-C
Atomic property can be accessed by only one thread at a time. It is thread safe. Default is atomic .Please note that there is no keyword atomic
Nonatomic means multiple thread can access the item .It is thread unsafe
So one should be very careful while using atomic .As it affect the performance of your code
How to call any method asynchronously in c#
Here's a way to do it:
// The method to call
void Foo()
{
}
Action action = Foo;
action.BeginInvoke(ar => action.EndInvoke(ar), null);
Of course you need to replace Action
by another type of delegate if the method has a different signature
Overloading operators in typedef structs (c++)
Instead of typedef struct { ... } pos;
you should be doing struct pos { ... };
. The issue here is that you are using the pos
type name before it is defined. By moving the name to the top of the struct definition, you are able to use that name within the struct definition itself.
Further, the typedef struct { ... } name;
pattern is a C-ism, and doesn't have much place in C++.
To answer your question about inline
, there is no difference in this case. When a method is defined within the struct/class definition, it is implicitly declared inline. When you explicitly specify inline
, the compiler effectively ignores it because the method is already declared inline.
(inline
methods will not trigger a linker error if the same method is defined in multiple object files; the linker will simply ignore all but one of them, assuming that they are all the same implementation. This is the only guaranteed change in behavior with inline methods. Nowadays, they do not affect the compiler's decision regarding whether or not to inline functions; they simply facilitate making the function implementation available in all translation units, which gives the compiler the option to inline the function, if it decides it would be beneficial to do so.)