Some Of The Best Answers From Latest Asked Questions
Handling 'Sequence has no elements' Exception
First() is causing this if your select returns 0 rows. You either have to catch that exception, or use FirstOrDefault() which will return null in case of no elements.
Do I need to pass the full path of a file in another directory to open()?
You have to specify the path that you are working on:
source = '/home/test/py_test/'
for root, dirs, filenames in os.walk(source):
for f in filenames:
print f
fullpath = os.path.join(source, f)
log = open(fullpath, 'r')
CMake unable to determine linker language with C++
In my case, it was just because there were no source file in the target. All of my library was template with source code in the header. Adding an empty file.cpp solved the problem.
Git: How to return from 'detached HEAD' state
You may have made some new commits in the detached HEAD state. I believe if you do as other answers advise:
git checkout master
# or
git checkout -
then you may lose your commits!! Instead, you may want to do this:
# you are currently in detached HEAD state
git checkout -b commits-from-detached-head
and then merge commits-from-detached-head into whatever branch you want, so you don't lose the commits.
HTML table needs spacing between columns, not rows
If you can use inline styling, you can set the left and right padding on each td.. Or you use an extra td between columns and set a number of non-breaking spaces as @rene kindly suggested.
Both are pretty ugly ;p css ftw
Using ping in c#
Imports System.Net.NetworkInformation
Public Function PingHost(ByVal nameOrAddress As String) As Boolean
Dim pingable As Boolean = False
Dim pinger As Ping
Dim lPingReply As PingReply
Try
pinger = New Ping()
lPingReply = pinger.Send(nameOrAddress)
MessageBox.Show(lPingReply.Status)
If lPingReply.Status = IPStatus.Success Then
pingable = True
Else
pingable = False
End If
Catch PingException As Exception
pingable = False
End Try
Return pingable
End Function
Should I use px or rem value units in my CSS?
TL;DR: use px.
The Facts
First, it's extremely important to know that per spec, the CSS
pxunit does not equal one physical display pixel. This has always been true – even in the 1996 CSS 1 spec.CSS defines the reference pixel, which measures the size of a pixel on a 96 dpi display. On a display that has a dpi substantially different than 96dpi (like Retina displays), the user agent rescales the
pxunit so that its size matches that of a reference pixel. In other words, this rescaling is exactly why 1 CSS pixel equals 2 physical Retina display pixels.That said, up until 2010 (and the mobile zoom situation notwithstanding), the
pxalmost always did equal one physical pixel, because all widely available displays were around 96dpi.Sizes specified in
ems are relative to the parent element. This leads to theem's "compounding problem" where nested elements get progressively larger or smaller. For example:body { font-size:20px; } div { font-size:0.5em; }Gives us:
<body> - 20px <div> - 10px <div> - 5px <div> - 2.5px <div> - 1.25pxThe CSS3
rem, which is always relative only to the roothtmlelement, is now supported on 96% of all browsers in use.
The Opinion
I think everyone agrees that it's good to design your pages to be accommodating to everyone, and to make consideration for the visually impaired. One such consideration (but not the only one!) is allowing users to make the text of your site bigger, so that it's easier to read.
In the beginning, the only way to provide users a way to scale text size was by using relative size units (such as ems). This is because the browser's font size menu simply changed the root font size. Thus, if you specified font sizes in px, they wouldn't scale when changing the browser's font size option.
Modern browsers (and even the not-so-modern IE7) all changed the default scaling method to simply zooming in on everything, including images and box sizes. Essentially, they make the reference pixel larger or smaller.
Yes, someone could still change their browser default stylesheet to tweak the default font size (the equivalent of the old-style font size option), but that's a very esoteric way of going about it and I'd wager nobody1 does it. (In Chrome, it's buried under the advanced settings, Web content, Font Sizes. In IE9, it's even more hidden. You have to press Alt, and go to View, Text Size.) It's much easier to just select the Zoom option in the browser's main menu (or use Ctrl++/-/mouse wheel).
1 - within statistical error, naturally
If we assume most users scale pages using the zoom option, I find relative units mostly irrelevant. It's much easier to develop your page when everything is specified in the same unit (images are all dealt with in pixels), and you don't have to worry about compounding. ("I was told there would be no math" – there's dealing with having to calculate what 1.5em actually works out to.)
One other potential problem of using only relative units for font sizes is that user-resized fonts may break assumptions your layout makes. For example, this might lead to text getting clipped or running too long. If you use absolute units, you don't have to worry about unexpected font sizes from breaking your layout.
So my answer is use pixel units. I use px for everything. Of course, your situation may vary, and if you must support IE6 (may the gods of the RFCs have mercy on you), you'll have to use ems anyway.
trying to align html button at the center of the my page
Make all parent element with 100% width and 100% height and use display: table; and display:table-cell;, check the working sample.
<!DOCTYPE html>
<html>
<head>
<style>
html,body{height: 100%;}
body{width: 100%;}
</style>
</head>
<body style="display: table; background-color: #ff0000; ">
<div style="display: table-cell; vertical-align: middle; text-align: center;">
<button type="button" style="text-align: center;" class="btn btn-info">
Discover More
</button>
</div>
</body>
</html>
How to find lines containing a string in linux
/tmp/myfile
first line text
wanted text
other text
the command
$ grep -n "wanted text" /tmp/myfile | awk -F ":" '{print $1}'
2
Getting HTTP code in PHP using curl
use this hitCurl method for fetch all type of api response i.e. Get / Post
function hitCurl($url,$param = [],$type = 'POST'){
$ch = curl_init();
if(strtoupper($type) == 'GET'){
$param = http_build_query((array)$param);
$url = "{$url}?{$param}";
}else{
curl_setopt_array($ch,[
CURLOPT_POST => (strtoupper($type) == 'POST'),
CURLOPT_POSTFIELDS => (array)$param,
]);
}
curl_setopt_array($ch,[
CURLOPT_URL => $url,
CURLOPT_RETURNTRANSFER => true,
]);
$resp = curl_exec($ch);
$statusCode = curl_getinfo($ch,CURLINFO_HTTP_CODE);
curl_close($ch);
return [
'statusCode' => $statusCode,
'resp' => $resp
];
}
Demo function to test api
function fetchApiData(){
$url = 'https://postman-echo.com/get';
$resp = $this->hitCurl($url,[
'foo1'=>'bar1',
'foo2'=>'bar2'
],'get');
$apiData = "Getting header code {$resp['statusCode']}";
if($resp['statusCode'] == 200){
$apiData = json_decode($resp['resp']);
}
echo "<pre>";
print_r ($apiData);
echo "</pre>";
}
git pull error :error: remote ref is at but expected
I faced same issue , I just deleted the remote branch and created new branch from the master and merged my changes from old feature branch to new feature branch . Now i tried pull and push requests its worked for me
Check if one list contains element from the other
If you want to check if an element exists in a list, use the contains method.
if (list1.contains(Object o))
{
//do this
}
Instagram how to get my user id from username?
Here is how you can retrieve your user id from a username:
$url = "https://api.instagram.com/v1/users/search?q=[username]&access_token=[your_token]";
$obj = json_decode(@file_get_contents($url));
echo $obj->data[0]->id;
Div show/hide media query
It sounds like you may be wanting to access the viewport of the device. You can do this by inserting this meta tag in your header.
<meta name="viewport" content="width=device-width, initial-scale=1.0">
Is there a way to provide named parameters in a function call in JavaScript?
Trying Node-6.4.0 ( process.versions.v8 = '5.0.71.60') and Node Chakracore-v7.0.0-pre8 and then Chrome-52 (V8=5.2.361.49), I've noticed that named parameters are almost implemented, but that order has still precedence. I can't find what the ECMA standard says.
>function f(a=1, b=2){ console.log(`a=${a} + b=${b} = ${a+b}`) }
> f()
a=1 + b=2 = 3
> f(a=5)
a=5 + b=2 = 7
> f(a=7, b=10)
a=7 + b=10 = 17
But order is required!! Is it the standard behaviour?
> f(b=10)
a=10 + b=2 = 12
XAMPP on Windows - Apache not starting
The most likely reason would be that something else is using port 80. (Often this can be Skype, IIS, etc.)
This tutorials shows How to Change the Apache Port in XAMPP
Add primary key to existing table
ALTER TABLE TABLE_NAME ADD PRIMARY KEY(`persionId`,`Pname`,`PMID`)
Setting new value for an attribute using jQuery
It is working you have to check attr after assigning value
$('#amount').attr( 'datamin','1000');
alert($('#amount').attr( 'datamin'));?
Find and Replace text in the entire table using a MySQL query
Another option is to generate the statements for each column in the database:
SELECT CONCAT(
'update ', table_name ,
' set ', column_name, ' = replace(', column_name,', ''www.oldDomain.com'', ''www.newDomain.com'');'
) AS statement
FROM information_schema.columns
WHERE table_schema = 'mySchema' AND table_name LIKE 'yourPrefix_%';
This should generate a list of update statements that you can then execute.
Removing white space around a saved image in matplotlib
You may try this. It solved my issue.
import matplotlib.image as mpimg
img = mpimg.imread("src.png")
mpimg.imsave("out.png", img, cmap=cmap)
Await operator can only be used within an Async method
You can only use await in an async method, and Main cannot be async.
You'll have to use your own async-compatible context, call Wait on the returned Task in the Main method, or just ignore the returned Task and just block on the call to Read. Note that Wait will wrap any exceptions in an AggregateException.
If you want a good intro, see my async/await intro post.
How do I delete everything below row X in VBA/Excel?
This function will clear the sheet data starting from specified row and column :
Sub ClearWKSData(wksCur As Worksheet, iFirstRow As Integer, iFirstCol As Integer)
Dim iUsedCols As Integer
Dim iUsedRows As Integer
iUsedRows = wksCur.UsedRange.Row + wksCur.UsedRange.Rows.Count - 1
iUsedCols = wksCur.UsedRange.Column + wksCur.UsedRange.Columns.Count - 1
If iUsedRows > iFirstRow And iUsedCols > iFirstCol Then
wksCur.Range(wksCur.Cells(iFirstRow, iFirstCol), wksCur.Cells(iUsedRows, iUsedCols)).Clear
End If
End Sub
cURL POST command line on WINDOWS RESTful service
- Try to use double quotes (") instead of single ones (').
- To preserve JSON format quotes, try doubling them ("").
To preserve quotes inside data, try to double-escape them like this (\\"").
curl ... -d "{""data1"": ""data1 goes here"", ""data2"": ""data2 goes here""}" curl ... -d "{""data"": ""data \\""abc\\"" goes here""}"
How do you handle a "cannot instantiate abstract class" error in C++?
The error means there are some methods of the class that aren't implemented. You cannot instantiate such a class, so there isn't anything you can do, other than implement all of the methods of the class.
On the other hand, a common pattern is to instantiate a concrete class and assign it to a pointer of an abstrate base class:
class Abstract { /* stuff */ 4};
class Derived : virtual public Abstract { /* implement Abstract's methods */ };
Abstract* pAbs = new Derived; // OK
Just an aside, to avoid memory management issues with the above line, you could consider using a smart pointer, such as an `std::unique_ptr:
std::unique_ptr<Abstract> pAbs(new Derived);
HTML Input="file" Accept Attribute File Type (CSV)
In addition to the top-answer, CSV files, for example, are reported as text/plain under macOS but as application/vnd.ms-excel under Windows. So I use this:
<input type="file" accept="text/plain, .csv, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/vnd.ms-excel" />
Round to at most 2 decimal places (only if necessary)
MarkG's answer is the correct one. Here's a generic extension for any number of decimal places.
Number.prototype.round = function(places) {
return +(Math.round(this + "e+" + places) + "e-" + places);
}
Usage:
var n = 1.7777;
n.round(2); // 1.78
Unit test:
it.only('should round floats to 2 places', function() {
var cases = [
{ n: 10, e: 10, p:2 },
{ n: 1.7777, e: 1.78, p:2 },
{ n: 1.005, e: 1.01, p:2 },
{ n: 1.005, e: 1, p:0 },
{ n: 1.77777, e: 1.8, p:1 }
]
cases.forEach(function(testCase) {
var r = testCase.n.round(testCase.p);
assert.equal(r, testCase.e, 'didn\'t get right number');
});
})
tmux set -g mouse-mode on doesn't work
Just a quick heads-up to anyone else who is losing their mind right now:
https://github.com/tmux/tmux/blob/310f0a960ca64fa3809545badc629c0c166c6cd2/CHANGES#L12
so that's just
:setw -g mouse
if (boolean == false) vs. if (!boolean)
This is a style choice. It does not impact the performance of the code in the least, it just makes it more verbose for the reader.
How to get bitmap from a url in android?
This should do the trick:
public static Bitmap getBitmapFromURL(String src) {
try {
URL url = new URL(src);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
return myBitmap;
} catch (IOException e) {
e.printStackTrace();
return null;
}
} // Author: silentnuke
Don't forget to add the internet permission in your manifest.
CAST to DECIMAL in MySQL
DECIMAL has two parts: Precision and Scale. So part of your query will look like this:
CAST((COUNT(*) * 1.5) AS DECIMAL(8,2))
Precision represents the number of significant digits that are stored for values.
Scale represents the number of digits that can be stored following the decimal point.
Multiple submit buttons in the same form calling different Servlets
You may need to write a javascript for each button submit. Instead of defining action in form definition, set those values in javascript. Something like below.
function callButton1(form, yourServ)
{
form.action = yourServ;
form.submit();
});
C++ passing an array pointer as a function argument
int *a[], when used as a function parameter (but not in normal declarations), is a pointer to a pointer, not a pointer to an array (in normal declarations, it is an array of pointers). A pointer to an array looks like this:
int (*aptr)[N]
Where N is a particular positive integer (not a variable).
If you make your function a template, you can do it and you don't even need to pass the size of the array (because it is automatically deduced):
template<size_t SZ>
void generateArray(int (*aptr)[SZ])
{
for (size_t i=0; i<SZ; ++i)
(*aptr)[i] = rand() % 9;
}
int main()
{
int a[5];
generateArray(&a);
}
You could also take a reference:
template<size_t SZ>
void generateArray(int (&arr)[SZ])
{
for (size_t i=0; i<SZ; ++i)
arr[i] = rand() % 9;
}
int main()
{
int a[5];
generateArray(a);
}
twitter-bootstrap: how to get rid of underlined button text when hovering over a btn-group within an <a>-tag?
a:hover, /* OPTIONAL*/
a:visited,
a:focus
{text-decoration: none !important;}
Convert Java Object to JsonNode in Jackson
As of Jackson 1.6, you can use:
JsonNode node = mapper.valueToTree(map);
or
JsonNode node = mapper.convertValue(object, JsonNode.class);
Source: is there a way to serialize pojo's directly to treemodel?
How do I exit the Vim editor?
Before you enter a command, hit the Esc key. After you enter it, hit the Return to confirm.
Esc finishes the current command and switches Vim to normal mode. Now if you press :, the : will appear at the bottom of the screen. This confirms that you're actually typing a command and not editing the file.
Most commands have abbreviations, with optional part enclosed in brackets: c[ommand].
Commands marked with '*' are Vim-only (not implemented in Vi).
Safe-quit (fails if there are unsaved changes):
:q[uit]Quit the current window. Quit Vim if this is the last window. This fails when changes have been made in current buffer.:qa[ll]* Quit all windows and Vim, unless there are some buffers which have been changed.
Prompt-quit (prompts if there are unsaved changes)
:conf[irm] q[uit]* Quit, but give prompt when there are some buffers which have been changed.:conf[irm] xa[ll]* Write all changed buffers and exit Vim. Bring up a prompt when some buffers cannot be written.
Write (save) changes and quit:
:wqWrite the current file (even if it was not changed) and quit. Writing fails when the file is read-only or the buffer does not have a name.:wqa[ll]* for all windows.:wq!The same, but writes even read-only files.:wqa[ll]!* for all windows.:x[it],ZZ(with details). Write the file only if it was changed and quit,:xa[ll]* for all windows.
Discard changes and quit:
:q[uit]!ZQ* Quit without writing, also when visible buffers have changes. Does not exit when there are changed hidden buffers.:qa[ll]!*,:quita[ll][!]* Quit Vim, all changes to the buffers (including hidden) are lost.
Press Return to confirm the command.
This answer doesn't reference all Vim write and quit commands and arguments. Indeed, they are referenced in the Vim documentation.
Vim has extensive built-in help, type Esc:helpReturn to open it.
This answer was inspired by the other one, originally authored by @dirvine and edited by other SO users. I've included more information from Vim reference, SO comments and some other sources. Differences for Vi and Vim are reflected too.
PHP - Insert date into mysql
Unless you want to insert different dates than "today", you can use CURDATE():
$sql = 'INSERT INTO data_tables (title, date_of_event) VALUES ("%s", CURDATE())';
$sql = sprintf ($sql, $_POST['post_title']);
PS! Please do not forget to sanitize your MySQL input, especially via mysql_real_escape_string ()
Calling a JSON API with Node.js
Problems with other answers:
- unsafe
JSON.parse - no response code checking
All of the answers here use JSON.parse() in an unsafe way.
You should always put all calls to JSON.parse() in a try/catch block especially when you parse JSON coming from an external source, like you do here.
You can use request to parse the JSON automatically which wasn't mentioned here in other answers. There is already an answer using request module but it uses JSON.parse() to manually parse JSON - which should always be run inside a try {} catch {} block to handle errors of incorrect JSON or otherwise the entire app will crash. And incorrect JSON happens, trust me.
Other answers that use http also use JSON.parse() without checking for exceptions that can happen and crash your application.
Below I'll show few ways to handle it safely.
All examples use a public GitHub API so everyone can try that code safely.
Example with request
Here's a working example with request that automatically parses JSON:
'use strict';
var request = require('request');
var url = 'https://api.github.com/users/rsp';
request.get({
url: url,
json: true,
headers: {'User-Agent': 'request'}
}, (err, res, data) => {
if (err) {
console.log('Error:', err);
} else if (res.statusCode !== 200) {
console.log('Status:', res.statusCode);
} else {
// data is already parsed as JSON:
console.log(data.html_url);
}
});
Example with http and try/catch
This uses https - just change https to http if you want HTTP connections:
'use strict';
var https = require('https');
var options = {
host: 'api.github.com',
path: '/users/rsp',
headers: {'User-Agent': 'request'}
};
https.get(options, function (res) {
var json = '';
res.on('data', function (chunk) {
json += chunk;
});
res.on('end', function () {
if (res.statusCode === 200) {
try {
var data = JSON.parse(json);
// data is available here:
console.log(data.html_url);
} catch (e) {
console.log('Error parsing JSON!');
}
} else {
console.log('Status:', res.statusCode);
}
});
}).on('error', function (err) {
console.log('Error:', err);
});
Example with http and tryjson
This example is similar to the above but uses the tryjson module. (Disclaimer: I am the author of that module.)
'use strict';
var https = require('https');
var tryjson = require('tryjson');
var options = {
host: 'api.github.com',
path: '/users/rsp',
headers: {'User-Agent': 'request'}
};
https.get(options, function (res) {
var json = '';
res.on('data', function (chunk) {
json += chunk;
});
res.on('end', function () {
if (res.statusCode === 200) {
var data = tryjson.parse(json);
console.log(data ? data.html_url : 'Error parsing JSON!');
} else {
console.log('Status:', res.statusCode);
}
});
}).on('error', function (err) {
console.log('Error:', err);
});
Summary
The example that uses request is the simplest. But if for some reason you don't want to use it then remember to always check the response code and to parse JSON safely.
Inner Joining three tables
dbo.tableA AS A INNER JOIN dbo.TableB AS B
ON A.common = B.common INNER JOIN TableC C
ON B.common = C.common
SSH SCP Local file to Remote in Terminal Mac Os X
Watch that your file name doesn't have : in them either. I found that I had to mv blah-07-08-17-02:69.txt no_colons.txt and then scp no-colons.txt server: then don't forget to mv back on the server. Just in case this was an issue.
Why use a ReentrantLock if one can use synchronized(this)?
ReentrantReadWriteLock is a specialized lock whereas synchronized(this) is a general purpose lock. They are similar but not quite the same.
You are right in that you could use synchronized(this) instead of ReentrantReadWriteLock but the opposite is not always true.
If you'd like to better understand what makes ReentrantReadWriteLock special look up some information about producer-consumer thread synchronization.
In general you can remember that whole-method synchronization and general purpose synchronization (using the synchronized keyword) can be used in most applications without thinking too much about the semantics of the synchronization but if you need to squeeze performance out of your code you may need to explore other more fine-grained, or special-purpose synchronization mechanisms.
By the way, using synchronized(this) - and in general locking using a public class instance - can be problematic because it opens up your code to potential dead-locks because somebody else not knowingly might try to lock against your object somewhere else in the program.
Converting String to Cstring in C++
vector<char> toVector( const std::string& s ) {
string s = "apple";
vector<char> v(s.size()+1);
memcpy( &v.front(), s.c_str(), s.size() + 1 );
return v;
}
vector<char> v = toVector(std::string("apple"));
// what you were looking for (mutable)
char* c = v.data();
.c_str() works for immutable. The vector will manage the memory for you.
How to get all selected values from <select multiple=multiple>?
$('#select-meal-type :selected') will contain an array of all of the selected items.
$('#select-meal-type option:selected').each(function() {
alert($(this).val());
});
?
Twig ternary operator, Shorthand if-then-else
{{ (ability.id in company_abilities) ? 'selected' : '' }}
The ternary operator is documented under 'other operators'
How to pass a file path which is in assets folder to File(String path)?
Unless you unpack them, assets remain inside the apk. Accordingly, there isn't a path you can feed into a File. The path you've given in your question will work with/in a WebView, but I think that's a special case for WebView.
You'll need to unpack the file or use it directly.
If you have a Context, you can use context.getAssets().open("myfoldername/myfilename"); to open an InputStream on the file. With the InputStream you can use it directly, or write it out somewhere (after which you can use it with File).
Regular expression search replace in Sublime Text 2
By the way, in the question above:
For:
Hello, my name is bob
Find part:
my name is (\w)+
With replace part:
my name used to be \1
Would return:
Hello, my name used to be b
Change find part to:
my name is (\w+)
And replace will be what you expect:
Hello, my name used to be bob
While (\w)+ will match "bob", it is not the grouping you want for replacement.
CSS - center two images in css side by side
I've just done this for a project, and achieved it by using the h6 tag which I wasn't using for anything else:
in html code:
<h6><img alt="small drawing" src="../Images/image1.jpg" width="50%"/> <img alt="small drawing" src="../Images/image2.jpg" width="50%"/><br/>Optional caption text</h6>
The space between the image tags puts a vertical gap between the images. The width argument in each img tag is optional, but it neatly sizes the images to fill the width of the page. Notice that each image must be set to take up only 50% of the width. (Or 33% if you're using 3 images.) The width argument must come after the alt and src arguments or it won't work.
in css code:
/* h6: set presentation of images */
h6
{
font-family: "Franklin Gothic Demi", serif;
font-size: 1.0em;
font-weight: normal;
line-height: 1.25em;
text-align: center;
}
The text items set the look of the caption text, and the text-align property centers both the images and the caption text.
MySQL Trigger: Delete From Table AFTER DELETE
I think there is an error in the trigger code. As you want to delete all rows with the deleted patron ID, you have to use old.id (Otherwise it would delete other IDs)
Try this as the new trigger:
CREATE TRIGGER log_patron_delete AFTER DELETE on patrons
FOR EACH ROW
BEGIN
DELETE FROM patron_info
WHERE patron_info.pid = old.id;
END
Dont forget the ";" on the delete query. Also if you are entering the TRIGGER code in the console window, make use of the delimiters also.
cell format round and display 2 decimal places
Another way is to use FIXED function, you can specify the number of decimal places but it defaults to 2 if the places aren't specified, i.e.
=FIXED(E5,2)
or just
=FIXED(E5)
Understanding the basics of Git and GitHub
What is the difference between Git and GitHub?
Git is a version control system; think of it as a series of snapshots (commits) of your code. You see a path of these snapshots, in which order they where created. You can make branches to experiment and come back to snapshots you took.
GitHub, is a web-page on which you can publish your Git repositories and collaborate with other people.
Is Git saving every repository locally (in the user's machine) and in GitHub?
No, it's only local. You can decide to push (publish) some branches on GitHub.
Can you use Git without GitHub? If yes, what would be the benefit for using GitHub?
Yes, Git runs local if you don't use GitHub. An alternative to using GitHub could be running Git on files hosted on Dropbox, but GitHub is a more streamlined service as it was made especially for Git.
How does Git compare to a backup system such as Time Machine?
It's a different thing, Git lets you track changes and your development process. If you use Git with GitHub, it becomes effectively a backup. However usually you would not push all the time to GitHub, at which point you do not have a full backup if things go wrong. I use git in a folder that is synchronized with Dropbox.
Is this a manual process, in other words if you don't commit you won't have a new version of the changes made?
Yes, committing and pushing are both manual.
If are not collaborating and you are already using a backup system why would you use Git?
If you encounter an error between commits you can use the command
git diffto see the differences between the current code and the last working commit, helping you to locate your error.You can also just go back to the last working commit.
If you want to try a change, but are not sure that it will work. You create a branch to test you code change. If it works fine, you merge it to the main branch. If it does not you just throw the branch away and go back to the main branch.
You did some debugging. Before you commit you always look at the changes from the last commit. You see your debug print statement that you forgot to delete.
Make sure you check gitimmersion.com.
pycharm convert tabs to spaces automatically
Just ot note: Pycharm's to spaces function only works on indent tabs at the beginning of a line, not interstitial tabs within a line of text. for example, when you are trying to format columns in monospaced text.
Cannot kill Python script with Ctrl-C
Ctrl+C terminates the main thread, but because your threads aren't in daemon mode, they keep running, and that keeps the process alive. We can make them daemons:
f = FirstThread()
f.daemon = True
f.start()
s = SecondThread()
s.daemon = True
s.start()
But then there's another problem - once the main thread has started your threads, there's nothing else for it to do. So it exits, and the threads are destroyed instantly. So let's keep the main thread alive:
import time
while True:
time.sleep(1)
Now it will keep print 'first' and 'second' until you hit Ctrl+C.
Edit: as commenters have pointed out, the daemon threads may not get a chance to clean up things like temporary files. If you need that, then catch the KeyboardInterrupt on the main thread and have it co-ordinate cleanup and shutdown. But in many cases, letting daemon threads die suddenly is probably good enough.
How to read/write arbitrary bits in C/C++
Some 2+ years after I asked this question I'd like to explain it the way I'd want it explained back when I was still a complete newb and would be most beneficial to people who want to understand the process.
First of all, forget the "11111111" example value, which is not really all that suited for the visual explanation of the process. So let the initial value be 10111011 (187 decimal) which will be a little more illustrative of the process.
1 - how to read a 3 bit value starting from the second bit:
___ <- those 3 bits
10111011
The value is 101, or 5 in decimal, there are 2 possible ways to get it:
- mask and shift
In this approach, the needed bits are first masked with the value 00001110 (14 decimal) after which it is shifted in place:
___
10111011 AND
00001110 =
00001010 >> 1 =
___
00000101
The expression for this would be: (value & 14) >> 1
- shift and mask
This approach is similar, but the order of operations is reversed, meaning the original value is shifted and then masked with 00000111 (7) to only leave the last 3 bits:
___
10111011 >> 1
___
01011101 AND
00000111
00000101
The expression for this would be: (value >> 1) & 7
Both approaches involve the same amount of complexity, and therefore will not differ in performance.
2 - how to write a 3 bit value starting from the second bit:
In this case, the initial value is known, and when this is the case in code, you may be able to come up with a way to set the known value to another known value which uses less operations, but in reality this is rarely the case, most of the time the code will know neither the initial value, nor the one which is to be written.
This means that in order for the new value to be successfully "spliced" into byte, the target bits must be set to zero, after which the shifted value is "spliced" in place, which is the first step:
___
10111011 AND
11110001 (241) =
10110001 (masked original value)
The second step is to shift the value we want to write in the 3 bits, say we want to change that from 101 (5) to 110 (6)
___
00000110 << 1 =
___
00001100 (shifted "splice" value)
The third and final step is to splice the masked original value with the shifted "splice" value:
10110001 OR
00001100 =
___
10111101
The expression for the whole process would be: (value & 241) | (6 << 1)
Bonus - how to generate the read and write masks:
Naturally, using a binary to decimal converter is far from elegant, especially in the case of 32 and 64 bit containers - decimal values get crazy big. It is possible to easily generate the masks with expressions, which the compiler can efficiently resolve during compilation:
- read mask for "mask and shift":
((1 << fieldLength) - 1) << (fieldIndex - 1), assuming that the index at the first bit is 1 (not zero) - read mask for "shift and mask":
(1 << fieldLength) - 1(index does not play a role here since it is always shifted to the first bit - write mask : just invert the "mask and shift" mask expression with the
~operator
How does it work (with the 3bit field beginning at the second bit from the examples above)?
00000001 << 3
00001000 - 1
00000111 << 1
00001110 ~ (read mask)
11110001 (write mask)
The same examples apply to wider integers and arbitrary bit width and position of the fields, with the shift and mask values varying accordingly.
Also note that the examples assume unsigned integer, which is what you want to use in order to use integers as portable bit-field alternative (regular bit-fields are in no way guaranteed by the standard to be portable), both left and right shift insert a padding 0, which is not the case with right shifting a signed integer.
Even easier:
Using this set of macros (but only in C++ since it relies on the generation of member functions):
#define GETMASK(index, size) ((((size_t)1 << (size)) - 1) << (index))
#define READFROM(data, index, size) (((data) & GETMASK((index), (size))) >> (index))
#define WRITETO(data, index, size, value) ((data) = (((data) & (~GETMASK((index), (size)))) | (((value) << (index)) & (GETMASK((index), (size))))))
#define FIELD(data, name, index, size) \
inline decltype(data) name() const { return READFROM(data, index, size); } \
inline void set_##name(decltype(data) value) { WRITETO(data, index, size, value); }
You could go for something as simple as:
struct A {
uint bitData;
FIELD(bitData, one, 0, 1)
FIELD(bitData, two, 1, 2)
};
And have the bit fields implemented as properties you can easily access:
A a;
a.set_two(3);
cout << a.two();
Replace decltype with gcc's typeof pre-C++11.
Role/Purpose of ContextLoaderListener in Spring?
When you want to put your Servlet file in your custom location or with custom name, rather than the default naming convention [servletname]-servlet.xml and path under Web-INF/ ,then you can use ContextLoaderListener.
Eclipse C++: Symbol 'std' could not be resolved
You can rewrite the code likes this:
#include<iostream>
#include<stdio.h>
using namespace std;
CSS: Creating textured backgrounds
If you search for an image base-64 converter, you can embed some small image texture files as code into your @import url('') section of code. It will look like a lot of code; but at least all your data is now stored locally - rather than having to call a separate resource to load the image.
Example link: http://www.base64-image.de/
When I take a file from my own inventory of a simple icon in PNG format, and convert it to base-64, it looks like this in my CSS:
url('data:image/png;base64,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')
With your texture images, you'll want to employ a similar process.
javascript: get a function's variable's value within another function
Your nameContent scope is only inside first function. You'll never get it's value that way.
var nameContent; // now it's global!
function first(){
nameContent = document.getElementById('full_name').value;
}
function second() {
first();
y=nameContent;
alert(y);
}
second();
I'm trying to use python in powershell
This works for me permanently:
[Environment]::SetEnvironmentVariable("Path", "$env:Path;C:\Python27","User")
PHP Fatal error: Class 'PDO' not found
This can also happen if there is a php.ini file in the web app's current working directory. If one has been placed there to change certain settings, it will override the global one.
To avoid this problem, don't use a php.ini file to change settings; instead you can:
Does Arduino use C or C++?
Arduino doesn't run either C or C++. It runs machine code compiled from either C, C++ or any other language that has a compiler for the Arduino instruction set.
C being a subset of C++, if Arduino can "run" C++ then it can "run" C.
If you don't already know C nor C++, you should probably start with C, just to get used to the whole "pointer" thing. You'll lose all the object inheritance capabilities though.
Opening popup windows in HTML
HTML alone does not support this. You need to use some JS.
And also consider nowadays people use popup blocker in browsers.
<a href="javascript:window.open('document.aspx','mypopuptitle','width=600,height=400')">open popup</a>
Export DataTable to Excel with Open Xml SDK in c#
I wanted to add this answer because I used the primary answer from this question as my basis for exporting from a datatable to Excel using OpenXML but then transitioned to OpenXMLWriter when I found it to be much faster than the above method.
You can find the full details in my answer in the link below. My code is in VB.NET though, so you'll have to convert it.
"replace" function examples
Here's an example where I found the replace( ) function helpful for giving me insight. The problem required a long integer vector be changed into a character vector and with its integers replaced by given character values.
## figuring out replace( )
(test <- c(rep(1,3),rep(2,2),rep(3,1)))
which looks like
[1] 1 1 1 2 2 3
and I want to replace every 1 with an A and 2 with a B and 3 with a C
letts <- c("A","B","C")
so in my own secret little "dirty-verse" I used a loop
for(i in 1:3)
{test <- replace(test,test==i,letts[i])}
which did what I wanted
test
[1] "A" "A" "A" "B" "B" "C"
In the first sentence I purposefully left out that the real objective was to make the big vector of integers a factor vector and assign the integer values (levels) some names (labels).
So another way of doing the replace( ) application here would be
(test <- factor(test,labels=letts))
[1] A A A B B C
Levels: A B C
How to get an input text value in JavaScript
<script type="text/javascript">
function kk(){
var lol = document.getElementById('lolz').value;
alert(lol);
}
</script>
<body onload="onload();">
<input type="text" name="enter" class="enter" id="lolz" value=""/>
<input type="button" value="click" onclick="kk();"/>
</body>
use this
Replace contents of factor column in R dataframe
I bet the problem is when you are trying to replace values with a new one, one that is not currently part of the existing factor's levels:
levels(iris$Species)
# [1] "setosa" "versicolor" "virginica"
Your example was bad, this works:
iris$Species[iris$Species == 'virginica'] <- 'setosa'
This is what more likely creates the problem you were seeing with your own data:
iris$Species[iris$Species == 'virginica'] <- 'new.species'
# Warning message:
# In `[<-.factor`(`*tmp*`, iris$Species == "virginica", value = c(1L, :
# invalid factor level, NAs generated
It will work if you first increase your factor levels:
levels(iris$Species) <- c(levels(iris$Species), "new.species")
iris$Species[iris$Species == 'virginica'] <- 'new.species'
If you want to replace "species A" with "species B" you'd be better off with
levels(iris$Species)[match("oldspecies",levels(iris$Species))] <- "newspecies"
Android ADB doesn't see device
What operating system are you on? If you running Windows you will want to make sure you have the drivers. You should also make sure that your Android SDK Manager is not only installed, but it also contains some additional things for different devices. Not sure if yours is in there or not.
Make sure that your phone has debugging enabled. I found myself having to run
adb kill-server
adb devices
often.
How do I delete an entity from symfony2
DELETE FROM ... WHERE id=...;
protected function templateRemove($id){
$em = $this->getDoctrine()->getManager();
$entity = $em->getRepository('XXXBundle:Templates')->findOneBy(array('id' => $id));
if ($entity != null){
$em->remove($entity);
$em->flush();
}
}
JRE 1.7 - java version - returns: java/lang/NoClassDefFoundError: java/lang/Object
Just did this on Solaris and ran into this identical problem where even "java -version" does not work. There is a reason that the 64 bit versions of the distro are WAY smaller than the 32-bit. It is indeed as stated above:
In other words, to get a fully working 64-bit installation, you must first run the 32-bit installation, and follow that up with a 64-bit installation if you have a 64bit capable machine...
So I ran the installer for the 32-bit:
sh jdk-6u131-solaris-sparc.sh
Then I ran the installer for the 64-bit:
sh jdk-6u131-solaris-sparcv9.sh
This gives me several java executables to choose from:
- $ find . -name java
- ./jdk1.6.0_131/db/demo/programs/scores/java
- ./jdk1.6.0_131/db/demo/programs/vtis/java
- ./jdk1.6.0_131/bin/java
- ./jdk1.6.0_131/bin/sparcv9/java
- ./jdk1.6.0_131/jre/bin/java
- ./jdk1.6.0_131/jre/bin/sparcv9/java
The sparcv9 java's are the 64bit versions and they work with "-version" when installed alongside the 32bit JDK.
- ./jdk1.6.0_131/bin/sparcv9/java -version
- java version "1.6.0_131"
- Java(TM) SE Runtime Environment (build 1.6.0_131-b32)
- Java HotSpot(TM) 64-Bit Server VM (build 20.131-b32, mixed mode)
-Dan
SQL order string as number
I was looking also a sorting fields that has letter prefix. Here is what i found out the solution. This might help who is looking for the same solution.
Field Values:
FL01,FL02,FL03,FL04,FL05,...FL100,...FL123456789
select SUBSTRING(field,3,9) as field from table order by SUBSTRING(field,3,10)*1 desc
SUBSTRING(field,3,9) i put 9 because 9 is way enough for me to hold max 9 digits integer values.
So the result will be 123456789 123456788 123456787 ... 100 99 ... 2 1
How do I select between the 1st day of the current month and current day in MySQL?
Complete solution for mysql current month and current year, which makes use of indexing properly as well :)
-- Current month
SELECT id, timestampfield
FROM table1
WHERE timestampfield >= DATE_SUB(CURRENT_DATE, INTERVAL DAYOFMONTH(CURRENT_DATE)-1 DAY)
AND timestampfield <= LAST_DAY(CURRENT_DATE);
-- Current year
SELECT id, timestampfield
FROM table1
WHERE timestampfield >= DATE_SUB(CURRENT_DATE, INTERVAL DAYOFYEAR(CURRENT_DATE)-1 DAY)
AND timestampfield <= LAST_DAY(CURRENT_DATE);
GROUP BY and COUNT in PostgreSQL
WITH uniq AS (
SELECT DISTINCT posts.id as post_id
FROM posts
JOIN votes ON votes.post_id = posts.id
-- GROUP BY not needed anymore
-- GROUP BY posts.id
)
SELECT COUNT(*)
FROM uniq;
How to make div background color transparent in CSS
Opacity gives you translucency or transparency. See an example Fiddle here.
-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)"; /* IE 8 */
filter: alpha(opacity=50); /* IE 5-7 */
-moz-opacity: 0.5; /* Netscape */
-khtml-opacity: 0.5; /* Safari 1.x */
opacity: 0.5; /* Good browsers */
Note: these are NOT CSS3 properties
See http://css-tricks.com/snippets/css/cross-browser-opacity/
AngularJS : ng-model binding not updating when changed with jQuery
You have to trigger the change event of the input element because ng-model listens to input events and the scope will be updated. However, the regular jQuery trigger didn't work for me. But here is what works like a charm
$("#myInput")[0].dispatchEvent(new Event("input", { bubbles: true })); //Works
Following didn't work
$("#myInput").trigger("change"); // Did't work for me
You can read more about creating and dispatching synthetic events.
AngularJS For Loop with Numbers & Ranges
For those new to angularjs. The index can be gotten by using $index.
For example:
<div ng-repeat="n in [] | range:10">
do something number {{$index}}
</div>
Which will, when you're using Gloopy's handy filter, print:
do something number 0
do something number 1
do something number 2
do something number 3
do something number 4
do something number 5
do something number 6
do something number 7
do something number 8
do something number 9
Adding placeholder text to textbox
there are BETTER solutions, but the easiest solution is here: set the textbox text to your desired string then create a function that deletes the text, have that function fire on textbox Focus Enter event
How to respond to clicks on a checkbox in an AngularJS directive?
Liviu's answer was extremely helpful for me. Hope this is not bad form but i made a fiddle that may help someone else out in the future.
Two important pieces that are needed are:
$scope.entities = [{
"title": "foo",
"id": 1
}, {
"title": "bar",
"id": 2
}, {
"title": "baz",
"id": 3
}];
$scope.selected = [];
java.sql.SQLException: Missing IN or OUT parameter at index:: 1
The first problem is that your query string is wrong:
I think this: "INSERT INTO employee(hans,germany) values(?,?)" should be like this: "INSERT INTO employee(name,country) values(?,?)"
The other problem is that you have a parameterized PreparedStatement and you don't set the parameters before running it.
You should add these to your code:
String inserting = "INSERT INTO employee(name,country) values(?,?)";
System.out.println("insert " + inserting);//
PreparedStatement ps = con.prepareStatement(inserting);
ps.setString(1,"hans"); // <----- this
ps.setString(2,"germany");// <---- and this
ps.executeUpdate();
How can I read input from the console using the Scanner class in Java?
You can make a simple program to ask for the user's name and print whatever the reply use inputs.
Or ask the user to enter two numbers and you can add, multiply, subtract, or divide those numbers and print the answers for user inputs just like the behavior of a calculator.
So there you need the Scanner class. You have to import java.util.Scanner;, and in the code you need to use:
Scanner input = new Scanner(System.in);
input is a variable name.
Scanner input = new Scanner(System.in);
System.out.println("Please enter your name: ");
s = input.next(); // Getting a String value
System.out.println("Please enter your age: ");
i = input.nextInt(); // Getting an integer
System.out.println("Please enter your salary: ");
d = input.nextDouble(); // Getting a double
See how this differs: input.next();, i = input.nextInt();, d = input.nextDouble();
According to a String, int and a double varies the same way for the rest. Don't forget the import statement at the top of your code.
Python: "TypeError: __str__ returned non-string" but still prints to output?
I Had the same problem, in my case, was because i was returned a digit:
def __str__(self):
return self.code
str is waiting for a str, not another.
now work good with:
def __str__(self):
return self.name
where name is a STRING.
pandas: filter rows of DataFrame with operator chaining
I had the same question except that I wanted to combine the criteria into an OR condition. The format given by Wouter Overmeire combines the criteria into an AND condition such that both must be satisfied:
In [96]: df
Out[96]:
A B C D
a 1 4 9 1
b 4 5 0 2
c 5 5 1 0
d 1 3 9 6
In [99]: df[(df.A == 1) & (df.D == 6)]
Out[99]:
A B C D
d 1 3 9 6
But I found that, if you wrap each condition in (... == True) and join the criteria with a pipe, the criteria are combined in an OR condition, satisfied whenever either of them is true:
df[((df.A==1) == True) | ((df.D==6) == True)]
Display alert message and redirect after click on accept
use this code to redirect the page
echo "<script>alert('There are no fields to generate a report');document.location='admin/ahm/panel'</script>";
How to make the web page height to fit screen height
Fixed positioning will do what you need:
#main
{
position:fixed;
top:0px;
bottom:0px;
left:0px;
right:0px;
}
How can I remove an entry in global configuration with git config?
Open config file to edit :
git config --global --edit
Press Insert and remove the setting
and finally type :wq and Enter to save.
Angularjs: input[text] ngChange fires while the value is changing
This is about recent additions to AngularJS, to serve as future answer (also for another question).
Angular newer versions (now in 1.3 beta), AngularJS natively supports this option, using ngModelOptions, like
ng-model-options="{ updateOn: 'default blur', debounce: { default: 500, blur: 0 } }"
Example:
<input type="text" name="username"
ng-model="user.name"
ng-model-options="{updateOn: 'default blur', debounce: {default: 500, blur: 0} }" />
IF a cell contains a string
=IFS(COUNTIF(A1,"*cats*"),"cats",COUNTIF(A1,"*22*"),"22",TRUE,"none")
Replace only text inside a div using jquery
Just in case if you can't change HTML. Very primitive but short & works. (It will empty the parent div hence the child divs will be removed)
$('#one').text('Hi I am replace');<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
_x000D_
<div id="one">_x000D_
<div class="first"></div>_x000D_
"Hi I am text"_x000D_
<div class="second"></div>_x000D_
<div class="third"></div>_x000D_
</div>How do I show a running clock in Excel?
Found the code that I referred to in my comment above. To test it, do this:
- In
Sheet1change the cell height and width of sayA1as shown in the snapshot below. - Format the cell by right clicking on it to show time format
- Add two buttons (form controls) on the worksheet and name them as shown in the snapshot
- Paste this code in a module
- Right click on the
Start Timerbutton on the sheet and click onAssign Macros. SelectStartTimermacro. - Right click on the
End Timerbutton on the sheet and click onAssign Macros. SelectEndTimermacro.
Now click on Start Timer button and you will see the time getting updated in cell A1. To stop time updates, Click on End Timer button.
Code (TRIED AND TESTED)
Public Declare Function SetTimer Lib "user32" ( _
ByVal HWnd As Long, ByVal nIDEvent As Long, _
ByVal uElapse As Long, ByVal lpTimerFunc As Long) As Long
Public Declare Function KillTimer Lib "user32" ( _
ByVal HWnd As Long, ByVal nIDEvent As Long) As Long
Public TimerID As Long, TimerSeconds As Single, tim As Boolean
Dim Counter As Long
'~~> Start Timer
Sub StartTimer()
'~~ Set the timer for 1 second
TimerSeconds = 1
TimerID = SetTimer(0&, 0&, TimerSeconds * 1000&, AddressOf TimerProc)
End Sub
'~~> End Timer
Sub EndTimer()
On Error Resume Next
KillTimer 0&, TimerID
End Sub
Sub TimerProc(ByVal HWnd As Long, ByVal uMsg As Long, _
ByVal nIDEvent As Long, ByVal dwTimer As Long)
'~~> Update value in Sheet 1
Sheet1.Range("A1").Value = Time
End Sub
SNAPSHOT
how to remove empty strings from list, then remove duplicate values from a list
To simplify Amiram Korach's solution:
dtList.RemoveAll(s => string.IsNullOrWhiteSpace(s))
No need to use Distinct() or ToList()
How to force a html5 form validation without submitting it via jQuery
To check whether a certain field is valid, use:
$('#myField')[0].checkValidity(); // returns true/false
To check if the form is valid, use:
$('#myForm')[0].checkValidity(); // returns true/false
If you want to display the native error messages that some browsers have (such as Chrome), unfortunately the only way to do that is by submitting the form, like this:
var $myForm = $('#myForm');
if(! $myForm[0].checkValidity()) {
// If the form is invalid, submit it. The form won't actually submit;
// this will just cause the browser to display the native HTML5 error messages.
$myForm.find(':submit').click();
}
Hope this helps. Keep in mind that HTML5 validation is not supported in all browsers.
How to prevent errno 32 broken pipe?
This might be because you are using two method for inserting data into database and this cause the site to slow down.
def add_subscriber(request, email=None):
if request.method == 'POST':
email = request.POST['email_field']
e = Subscriber.objects.create(email=email).save() <====
return HttpResponseRedirect('/')
else:
return HttpResponseRedirect('/')
In above function, the error is where arrow is pointing. The correct implementation is below:
def add_subscriber(request, email=None):
if request.method == 'POST':
email = request.POST['email_field']
e = Subscriber.objects.create(email=email)
return HttpResponseRedirect('/')
else:
return HttpResponseRedirect('/')
Handling a timeout error in python sockets
from foo import *
adds all the names without leading underscores (or only the names defined in the modules __all__ attribute) in foo into your current module.
In the above code with from socket import * you just want to catch timeout as you've pulled timeout into your current namespace.
from socket import * pulls in the definitions of everything inside of socket but doesn't add socket itself.
try:
# socketstuff
except timeout:
print 'caught a timeout'
Many people consider import * problematic and try to avoid it. This is because common variable names in 2 or more modules that are imported in this way will clobber one another.
For example, consider the following three python files:
# a.py
def foo():
print "this is a's foo function"
# b.py
def foo():
print "this is b's foo function"
# yourcode.py
from a import *
from b import *
foo()
If you run yourcode.py you'll see just the output "this is b's foo function".
For this reason I'd suggest either importing the module and using it or importing specific names from the module:
For example, your code would look like this with explicit imports:
import socket
from socket import AF_INET, SOCK_DGRAM
def main():
client_socket = socket.socket(AF_INET, SOCK_DGRAM)
client_socket.settimeout(1)
server_host = 'localhost'
server_port = 1234
while(True):
client_socket.sendto('Message', (server_host, server_port))
try:
reply, server_address_info = client_socket.recvfrom(1024)
print reply
except socket.timeout:
#more code
Just a tiny bit more typing but everything's explicit and it's pretty obvious to the reader where everything comes from.
Using If/Else on a data frame
Try this
frame$twohouses <- ifelse(frame$data>1, 2, 1)
frame
data twohouses
1 0 1
2 1 1
3 2 2
4 3 2
5 4 2
6 2 2
7 3 2
8 1 1
9 4 2
10 3 2
11 2 2
12 4 2
13 0 1
14 1 1
15 2 2
16 0 1
17 2 2
18 1 1
19 2 2
20 0 1
21 4 2
Whitespaces in java
From sun docs:
\s A whitespace character: [ \t\n\x0B\f\r]
The simplest way is to use it with regex.
GridLayout and Row/Column Span Woe
Android Support V7 GridLayout library makes excess space distribution easy by accommodating the principle of weight. To make a column stretch, make sure the components inside it define a weight or a gravity. To prevent a column from stretching, ensure that one of the components in the column does not define a weight or a gravity. Remember to add dependency for this library. Add com.android.support:gridlayout-v7:25.0.1 in build.gradle.
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:columnCount="2"
app:rowCount="2">
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:gravity="center"
android:text="First"
app:layout_columnWeight="1"
app:layout_rowWeight="1" />
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:gravity="center"
android:text="Second"
app:layout_columnWeight="1"
app:layout_rowWeight="1" />
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:gravity="center"
android:text="Third"
app:layout_columnWeight="1"
app:layout_rowWeight="1" />
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:gravity="center"
app:layout_columnWeight="1"
app:layout_rowWeight="1"
android:text="fourth"/>
</android.support.v7.widget.GridLayout>
how to get the attribute value of an xml node using java
use
document.getElementsByTagName(" * ");
to get all XML elements from within an XML file, this does however return repeating attributes
example:
NodeList list = doc.getElementsByTagName("*");
System.out.println("XML Elements: ");
for (int i=0; i<list.getLength(); i++) {
Element element = (Element)list.item(i);
System.out.println(element.getNodeName());
}
Attempt to present UIViewController on UIViewController whose view is not in the window hierarchy
If other solutions does not look good for some reason, you can still use this good old workaround of presenting with the delay of 0, like this:
dispatch_after(0, dispatch_get_main_queue(), ^{
finishViewController *finished = [self.storyboard instantiateViewControllerWithIdentifier:@"finishViewController"];
[self presentViewController:finished animated:NO completion:NULL];
});
While I've seen no documented guarantee that your VC would be on the view hierarchy on the time dispatch block is scheduled to execution, I've observed it would work just fine.
Using delay of e.g. 0.2 sec is also an option. And the best thing - this way you don't need to mess with boolean variable in viewDidAppear:
SQL Column definition : default value and not null redundant?
I would say not.
If the column does accept null values, then there's nothing to stop you inserting a null value into the field. As far as I'm aware, the default value only applies on creation of a new row.
With not null set, then you can't insert a null value into the field as it'll throw an error.
Think of it as a fail safe mechanism to prevent nulls.
Optional query string parameters in ASP.NET Web API
Use initial default values for all parameters like below
public string GetFindBooks(string author="", string title="", string isbn="", string somethingelse="", DateTime? date= null)
{
// ...
}
Find all files in a folder
First off; best practice would be to get the users Desktop folder with
string path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
Then you can find all the files with something like
string[] files = Directory.GetFiles(path, "*.txt", SearchOption.AllDirectories);
Note that with the above line you will find all files with a .txt extension in the Desktop folder of the logged in user AND all subfolders.
Then you could copy or move the files by enumerating the above collection like
// For copying...
foreach (string s in files)
{
File.Copy(s, "C:\newFolder\newFilename.txt");
}
// ... Or for moving
foreach (string s in files)
{
File.Move(s, "C:\newFolder\newFilename.txt");
}
Please note that you will have to include the filename in your Copy() (or Move()) operation. So you would have to find a way to determine the filename of at least the extension you are dealing with and not name all the files the same like what would happen in the above example.
With that in mind you could also check out the DirectoryInfo and FileInfo classes.
These work in similair ways, but you can get information about your path-/filenames, extensions, etc. more easily
Check out these for more info:
http://msdn.microsoft.com/en-us/library/system.io.directory.aspx
How to handle onchange event on input type=file in jQuery?
Try to use this:
HTML:
<input ID="fileUpload1" runat="server" type="file">
JavaScript:
$("#fileUpload1").on('change',function() {
alert('Works!!');
});
?