Programs & Examples On #Escape analysis

Escape analysis determines all the places where a pointer can be stored and whether the lifetime of the pointer can be proven to be restricted only to the current procedure and/or thread.

How to add a delay for a 2 or 3 seconds

For 2.3 seconds you should do:


Easiest way to develop simple GUI in Python

I would recommend wxpython. It's very easy to use and the documentation is pretty good.

How can I get the current time in C#?

DateTime.Now is what you're searching for...

Reference requirements.txt for the install_requires kwarg in setuptools file

Another possible solution...

def gather_requirements(top_path=None):
    """Captures requirements from repo.

    Expected file format is: requirements[-_]<optional-extras>.txt

    For example:

        pip install -e .[foo]

    Would require:




    from import PipSession
    from pip.req import parse_requirements
    import re

    session = PipSession()
    top_path = top_path or os.path.realpath(os.getcwd())
    extras = {}
    for filepath in tree(top_path):
        filename = os.path.basename(filepath)
        basename, ext = os.path.splitext(filename)
        if ext == '.txt' and basename.startswith('requirements'):
            if filename == 'requirements.txt':
                extra_name = 'requirements'
                _, extra_name = re.split(r'[-_]', basename, 1)
            if extra_name:
                reqs = [str(ir.req) for ir in parse_requirements(filepath, session=session)]
                extras.setdefault(extra_name, []).extend(reqs)
    all_reqs = set()
    for key, values in extras.items():
    extras['all'] = list(all_reqs)
    return extras

and then to use...

reqs = gather_requirements()
install_reqs = reqs.pop('requirements', [])
test_reqs = reqs.pop('test', [])
    'install_requires': install_reqs,
    'test_requires': test_reqs,
    'extras_require': reqs,

Python - 'ascii' codec can't decode byte

You can try this

import sys


You can also try following

Add following line at top of your .py file.

# -*- coding: utf-8 -*- 

iOS 6 apps - how to deal with iPhone 5 screen size?

I think you can use [UIScreen mainScreen].bounds.size.height and calculate step for your objects. when you calculate step you can set coordinates for two resolutions.

Or you can get height like above and if(iphone5) then... else if(iphone4) then... else if(ipad). Something like this.

If you use storyboards then you have to create new for new iPhone i think.

How to find char in string and get all the indexes?

As the rule of thumb, NumPy arrays often outperform other solutions while working with POD, Plain Old Data. A string is an example of POD and a character too. To find all the indices of only one char in a string, NumPy ndarrays may be the fastest way:

def find1(str, ch):
  # 0.100 seconds for 1MB str 
  npbuf = np.frombuffer(str, dtype=np.uint8) # Reinterpret str as a char buffer
  return np.where(npbuf == ord(ch))          # Find indices with numpy

def find2(str, ch):
  # 0.920 seconds for 1MB str 
  return [i for i, c in enumerate(str) if c == ch] # Find indices with python

Can we install Android OS on any Windows Phone and vice versa, and same with iPhone and vice versa?

Android needs to be compiled for every hardware plattform / every device model seperatly with the specific drivers etc. If you manage to do that you need also break the security arrangements every manufacturer implements to prevent the installation of other software - these are also different between each model / manufacturer. So it is possible at in theory, but only there :-)

How to make input type= file Should accept only pdf and xls

You could do so by using the attribute accept and adding allowed mime-types to it. But not all browsers do respect that attribute and it could easily be removed via some code inspector. So in either case you need to check the file type on the server side (your second question).


<input type="file" name="upload" accept="application/pdf,application/" />

To your third question "And when I click the files (PDF/XLS) on webpage it automatically should open.":

You can't achieve that. How a PDF or XLS is opened on the client machine is set by the user.

R for loop skip to next iteration ifelse

for(n in 1:5) {
  if(n==3) next # skip 3rd iteration and go to next iteration

How to stretch div height to fill parent div - CSS

If you're gonna use B2 for styling purposes you can try this "hack"

#B { overflow: hidden;}
#B2 {padding-bottom: 9999px; margin-bottom: -9999px}


How can I get current location from user in iOS

In iOS 6, the

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation

is deprecated.

Use following code instead

- (void)locationManager:(CLLocationManager *)manager
     didUpdateLocations:(NSArray *)locations {
    CLLocation *location = [locations lastObject];
    NSLog(@"lat%f - lon%f", location.coordinate.latitude, location.coordinate.longitude);

For iOS 6~8, the above method is still necessary, but you have to handle authorization.

_locationManager = [CLLocationManager new];
_locationManager.delegate = self;
_locationManager.distanceFilter = kCLDistanceFilterNone;
_locationManager.desiredAccuracy = kCLLocationAccuracyBest;

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0 &&
    [CLLocationManager authorizationStatus] != kCLAuthorizationStatusAuthorizedWhenInUse
    //[CLLocationManager authorizationStatus] != kCLAuthorizationStatusAuthorizedAlways
   ) {
     // Will open an confirm dialog to get user's approval 
    [_locationManager requestWhenInUseAuthorization]; 
    //[_locationManager requestAlwaysAuthorization];
} else {
    [_locationManager startUpdatingLocation]; //Will update location immediately 

This is the delegate method which handle user's authorization

#pragma mark - CLLocationManagerDelegate
- (void)locationManager:(CLLocationManager*)manager didChangeAuthorizationStatus:(CLAuthorizationStatus)status
    switch (status) {
    case kCLAuthorizationStatusNotDetermined: {
        NSLog(@"User still thinking..");
    } break;
    case kCLAuthorizationStatusDenied: {
        NSLog(@"User hates you");
    } break;
    case kCLAuthorizationStatusAuthorizedWhenInUse:
    case kCLAuthorizationStatusAuthorizedAlways: {
        [_locationManager startUpdatingLocation]; //Will update location immediately
    } break;

Best way to specify whitespace in a String.Split operation

So don't copy and paste! Extract a function to do your splitting and reuse it.

public static string[] SplitWhitespace (string input)
    char[] whitespace = new char[] { ' ', '\t' };
    return input.Split(whitespace);

Code reuse is your friend.

Iteration over std::vector: unsigned vs signed index variable

The first is type correct, and correct in some strict sense. (If you think about is, size can never be less than zero.) That warning strikes me as one of the good candidates for being ignored, though.

How to check if one DateTime is greater than the other in C#

You can use the overloaded < or > operators.

For example:

DateTime d1 = new DateTime(2008, 1, 1);
DateTime d2 = new DateTime(2008, 1, 2);
if (d1 < d2) { ...

PostgreSQL - query from bash script as database user 'postgres'

Once you're logged in as postgres, you should be able to write:

psql -t -d database_name -c $'SELECT c_defaults FROM user_info WHERE c_uid = \'testuser\';'

to print out just the value of that field, which means that you can capture it to (for example) save in a Bash variable:

testuser_defaults="$(psql -t -d database_name -c $'SELECT c_defaults FROM user_info WHERE c_uid = \'testuser\';')"

To handle the logging in as postgres, I recommend using sudo. You can give a specific user the permission to run

sudo -u postgres /path/to/this/

so that they can run just the one script as postgres.

Cross browser JavaScript (not jQuery...) scroll to top animation

function scrollTo(element, to, duration) {
    if (duration <= 0) return;
    var difference = to - element.scrollTop;
    var perTick = difference / duration * 10;

    setTimeout(function() {
        element.scrollTop = element.scrollTop + perTick;
        if (element.scrollTop === to) return;
        scrollTo(element, to, duration - 10);
    }, 10);


function runScroll() {_x000D_
  scrollTo(document.body, 0, 600);_x000D_
var scrollme;_x000D_
scrollme = document.querySelector("#scrollme");_x000D_
function scrollTo(element, to, duration) {_x000D_
  if (duration <= 0) return;_x000D_
  var difference = to - element.scrollTop;_x000D_
  var perTick = difference / duration * 10;_x000D_
  setTimeout(function() {_x000D_
    element.scrollTop = element.scrollTop + perTick;_x000D_
    if (element.scrollTop == to) return;_x000D_
    scrollTo(element, to, duration - 10);_x000D_
  }, 10);_x000D_
<p>Very long page.Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. 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Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page.  Very long page.Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page.  Very long page.Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page.  Very long page.Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page._x000D_
<button id=scrollme type="button">To the top</button>

Docker container not starting (docker start)

What I need is to use Docker with MariaDb on different port /3301/ on my Ubuntu machine because I already had MySql installed and running on 3306.

To do this after half day searching did it using:

docker run -it -d -p 3301:3306 -v ~/mdbdata/mariaDb:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=root --name mariaDb mariadb

This pulls the image with latest MariaDb, creates container called mariaDb, and run mysql on port 3301. All data of which is located in home directory in /mdbdata/mariaDb.

To login in mysql after that can use:

mysql -u root -proot -h -P3301

Used sources are:

The answer of Iarks in this article /using -it -d was the key :) /




Good luck all!

Using a Python subprocess call to invoke a Python script

Check out this.

from subprocess import call 
with open('directory_of_logfile/logfile.txt', 'w') as f:
   call(['python', 'directory_of_called_python_file/'], stdout=f)

Boto3 to download all files from a S3 Bucket

From AWS S3 Docs (How do I use folders in an S3 bucket?):

In Amazon S3, buckets and objects are the primary resources, and objects are stored in buckets. Amazon S3 has a flat structure instead of a hierarchy like you would see in a file system. However, for the sake of organizational simplicity, the Amazon S3 console supports the folder concept as a means of grouping objects. Amazon S3 does this by using a shared name prefix for objects (that is, objects have names that begin with a common string). Object names are also referred to as key names.

For example, you can create a folder on the console named photos and store an object named myphoto.jpg in it. The object is then stored with the key name photos/myphoto.jpg, where photos/ is the prefix.

To download all files from "mybucket" into the current directory respecting the bucket's emulated directory structure (creating the folders from the bucket if they don't already exist locally):

import boto3
import os

bucket_name = "mybucket"
s3 = boto3.client("s3")
objects = s3.list_objects(Bucket = bucket_name)["Contents"]
for s3_object in objects:
    s3_key = s3_object["Key"]
    path, filename = os.path.split(s3_key)
    if len(path) != 0 and not os.path.exists(path):
    if not s3_key.endswith("/"):
        download_to = path + '/' + filename if path else filename
        s3.download_file(bucket_name, s3_key, download_to)

Output data with no column headings using PowerShell

In your case, when you just select a single property, the easiest way is probably to bypass any formatting altogether:

get-qadgroupmember 'Domain Admins' | foreach { $_.Name }

This will get you a simple string[] without column headings or empty lines. The Format-* cmdlets are mainly for human consumption and thus their output is not designed to be easily machine-readable or -parseable.

For multiple properties I'd probably go with the -f format operator. Something along the lines of

alias | %{ "{0,-10}{1,-10}{2,-60}" -f $_.COmmandType,$_.Name,$_.Definition }

which isn't pretty but gives you easy and complete control over the output formatting. And no empty lines :-)

Find out which remote branch a local branch is tracking

If you are using Gradle,

def gitHash = new ByteArrayOutputStream()
    project.exec {
        commandLine 'git', 'rev-parse', '--short', 'HEAD'
        standardOutput = gitHash

def gitBranch = new ByteArrayOutputStream()
    project.exec {
        def gitCmd = "git symbolic-ref --short -q HEAD || git branch -rq --contains "+getGitHash()+" | sed -e '2,\$d'  -e 's/\\(.*\\)\\/\\(.*\\)\$/\\2/' || echo 'master'"
        commandLine "bash", "-c", "${gitCmd}"
        standardOutput = gitBranch

Python dictionary: are keys() and values() always the same order?

For what it's worth, some heavy used production code I have written is based on this assumption and I never had a problem with it. I know that doesn't make it true though :-)

If you don't want to take the risk I would use iteritems() if you can.

for key, value in myDictionary.iteritems():
    print key, value

CSS: Fix row height

    table tbody_x000D_
        border:1px solid red;_x000D_
    table td_x000D_
        border-bottom:1px solid green;_x000D_
     .tr0 td{_x000D_
    <tr><td>test</td></tr>    _x000D_
    <tr class="tr0"><td></td></tr>_x000D_

Adding and reading from a Config file

Configuration configManager = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
KeyValueConfigurationCollection confCollection = configManager.AppSettings.Settings;

confCollection["YourKey"].Value = "YourNewKey";


Detect if value is number in MySQL

This should work in most cases.

SELECT * FROM myTable WHERE concat('',col1 * 1) = col1

It doesn't work for non-standard numbers like

  • 1e4
  • 1.2e5
  • 123. (trailing decimal)

How to autoplay HTML5 mp4 video on Android?

don't use "mute" alone, use [muted]="true" for example following code:

<video id="videoPlayer" [muted]="true" autoplay playsinline loop style="width:100%; height: 100%;">
<source type="video/mp4" src="assets/Video/Home.mp4">
<source type="video/webm" src="assets/Video/Home.webm">

I test in more Android and ios

Which one is the best PDF-API for PHP?

Personally I prefer to use dompdf for simple PDF pages as it is very quick. you simply feed it an HTML source and it will generate the required page.

however for more complex designs i prefer the more classic pdflib which is available as a pecl for PHP. it has greater control over designs and allows you do do more complex designs like pixel-perfect forms.

Difference between Build Solution, Rebuild Solution, and Clean Solution in Visual Studio?

All I know is a Clean does not do what "make clean" used to do - if I Clean a solution I would expect it delete obj and bin files/folders such that it builds like is was a fresh checkout of the source. In my experience though I often find times where a Clean and Build or Rebuild still produces strange errors on source that is known to compile and what is required is a manual deletion of the bin/obj folders, then it will build.

Cleaning up old remote git branches

If git branch -r shows a lot of remote-tracking branches that you're not interested in and you want to remove them only from local, use the following command:

git branch -r | grep -Ev 'HEAD|master|develop'  | xargs -r git branch -rd

A safer version would be to only remove the merged ones:

git branch -r --merged | grep -Ev 'HEAD|master|develop'  | xargs -r git branch -rd

This might be useful for large projects, where you don't need the feature branches of other teammates but there're lots of remote-tracking branches fetched upon the initial clone.

However, this step alone is not sufficient, because those deleted remote-tracking branches would come back upon next git fetch.

To stop fetching those remote-tracking branches you need to explicitly specify the refs to fetch in .git/config:

[remote "origin"]
  # fetch = +refs/heads/*:refs/remotes/origin/*    ### don't fetch everything
  fetch = +refs/heads/master:refs/remotes/origin/master
  fetch = +refs/heads/develop:refs/remotes/origin/develop
  fetch = +refs/heads/release/*:refs/remotes/origin/release/*

In the above example we only fetch master, develop and release branches, feel free to adapt as you need.

How to convert hex to ASCII characters in the Linux shell?

Some python3 one-liners that work with any number of bytes.

Decoding hex (with strip, so that it's ok to have a newline on stdin):

$ echo 666f6f0a | python3 -c "import sys, binascii; sys.stdout.buffer.write(binascii.unhexlify(input().strip()))"

Encoding hex:

$ echo foo | python3 -c "import sys, binascii; print(binascii.hexlify("

How to combine two lists in R

c can be used on lists (and not only on vectors):

# you have
l1 = list(2, 3)
l2 = list(4)

# you want
list(2, 3, 4)
[1] 2

[1] 3

[1] 4

# you can do
c(l1, l2)
[1] 2

[1] 3

[1] 4

If you have a list of lists, you can do it (perhaps) more comfortably with, eg:, list(l1, l2))

How to remove unused imports in Intellij IDEA on commit?

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

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

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

List of tuples to dictionary

Just call dict() on the list of tuples directly

>>> my_list = [('a', 1), ('b', 2)]
>>> dict(my_list)
{'a': 1, 'b': 2}

Python: access class property from string

  • getattr(x, 'y') is equivalent to x.y
  • setattr(x, 'y', v) is equivalent to x.y = v
  • delattr(x, 'y') is equivalent to del x.y

The specified type member 'Date' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties

I would like to add a solution, that have helpt me to solve this problem in entity framework:

var eventsCustom = eventCustomRepository.FindAllEventsCustomByUniqueStudentReference(userDevice.UniqueStudentReference)
                .Where(x =>  x.DateTimeStart.Year == currentDateTime.Year &&
                             x.DateTimeStart.Month== currentDateTime.Month &&
                             x.DateTimeStart.Day == currentDateTime.Day

I hope that it helps.

How can I alter a primary key constraint using SQL syntax?

you can rename constraint objects using sp_rename (as described in this answer)

for example:

EXEC sp_rename N'schema.MyIOldConstraint', N'MyNewConstraint'

iptables v1.4.14: can't initialize iptables table `nat': Table does not exist (do you need to insmod?)

It maybe useful to add that if you're seeing this error message and you're not using some kind of restricted container based hosting (e.g. OpenVZ) then the problem maybe that the kernel is missing the nat modules. To check run:

modinfo iptable_nat

Which should print out the location of the module, if it prints an ERROR then you know that is your problem. There are also dependent modules like nf_nat which might be missing so you'll have to dig deeper if the iptable_nat module is there but fails. If it is missing you'll need to get another kernel and modules, or if you're rolling your own ensure that the kernel config contains CONFIG_IP_NF_NAT=m (for IPv4 NAT).

For info the relevant kernel module is usually found in one of these locations:

ls /lib/modules/`uname -r`/kernel/net/netfilter/
ls /lib/modules/`uname -r`/kernel/net/ipv4/netfilter/

And if you're running IPv6 also look here:

ls /lib/modules/`uname -r`/kernel/net/ipv6/netfilter/

Python 2.7: %d, %s, and float()

Try the following:

print "First is: %f" % (first)
print "Second is: %f" % (second)

I am unsure what answer is. But apart from that, this will be:

print "DONE: %f DIVIDED BY %f EQUALS %f, SWEET MATH BRO!" % (first, second, ans)

There's a lot of text on Format String Specifiers. You can google it and get a list of specifiers. One thing I forgot to note:

If you try this:

print "First is: %s" % (first)

It converts the float value in first to a string. So that would work as well.

Validating IPv4 addresses with regexp


Test to find matches in text,

Following are the rules defining the valid combinations in each number of an IP address:

  • Any one- or two-digit number.
  • Any three-digit number beginning with 1.

  • Any three-digit number beginning with 2 if the second digit is 0 through 4.

  • Any three-digit number beginning with 25 if the third digit is 0 through 5.

Let'start with (((25[0-5])|(2[0-4]\d)|(1\d{2})|(\d{1,2}))\.), a set of four nested subexpressions, and we’ll look at them in reverse order. (\d{1,2}) matches any one- or two-digit number or numbers 0 through 99. (1\d{2}) matches any three-digit number starting with 1 (1 followed by any two digits), or numbers 100 through 199. (2[0-4]\d) matches numbers 200 through 249. (25[0-5]) matches numbers 250 through 255. Each of these subexpressions is enclosed within another subexpression with an | between each (so that one of the four subexpressions has to match, not all). After the range of numbers comes \. to match ., and then the entire series (all the number options plus \.) is enclosed into yet another subexpression and repeated three times using {3}. Finally, the range of numbers is repeated (this time without the trailing \.) to match the final IP address number. By restricting each of the four numbers to values between 0 and 255, this pattern can indeed match valid IP addresses and reject invalid addresses.

Excerpt From: Ben Forta. “Learning Regular Expressions.”

If neither a character is wanted at the beginning of IP address nor at the end, ^ and $ metacharacters ought to be used, respectively.


Test to find matches in text,

Setting environment variables on OS X

Sometimes all of the previous answers simply don't work. If you want to have access to a system variable (like M2_HOME) in Eclipse or in IntelliJ IDEA the only thing that works for me in this case is:

First (step 1) edit /etc/launchd.conf to contain a line like this: "setenv VAR value" and then (step 2) reboot.

Simply modifying .bash_profile won't work because in OS X the applications are not started as in other Unix'es; they don't inherit the parent's shell variables. All the other modifications won't work for a reason that is unknown to me. Maybe someone else can clarify about this.

How to get a value from the last inserted row?

Don't use SELECT currval('MySequence') - the value gets incremented on inserts that fail.

How to set the font size in Emacs?

From Emacswiki, GNU Emacs 23 has a built-in key combination:

C-xC-+ and C-xC-- to increase or decrease the buffer text size

How to convert a column of DataTable to a List

Try this:

static void Main(string[] args)
    var dt = new DataTable
        Columns = { { "Lastname",typeof(string) }, { "Firstname",typeof(string) } }
    dt.Rows.Add("Lennon", "John");
    dt.Rows.Add("McCartney", "Paul");
    dt.Rows.Add("Harrison", "George");
    dt.Rows.Add("Starr", "Ringo");

    List<string> s = dt.AsEnumerable().Select(x => x[0].ToString()).ToList();

    foreach(string e in s)


How does strtok() split the string into tokens in C?

The first time you call it, you provide the string to tokenize to strtok. And then, to get the following tokens, you just give NULL to that function, as long as it returns a non NULL pointer.

The strtok function records the string you first provided when you call it. (Which is really dangerous for multi-thread applications)

How do I get the function name inside a function in PHP?

If you are using PHP 5 you can try this:

function a() {
    $trace = debug_backtrace();
    echo $trace[0]["function"];

SCRIPT7002: XMLHttpRequest: Network Error 0x2ef3, Could not complete the operation due to error 00002ef3

This is the fix that worked for me. There is invalid mime or bad characterset being sent with your json data causing that errror. Add the charset like this to help it from getting confused:

  contentType:"application/json; charset=utf-8",
  success: function(){


Jquery - How to make $.post() use contentType=application/json?

Could not complete the operation due to error c00ce56e

Laravel: getting a a single value from a MySQL query

Using query builder, get the single column value such as groupName

  $groupName = DB::table('users')->where('username', $username)->pluck('groupName');

For Laravel 5.1

 $groupName=DB::table('users')->where('username', $username)->value('groupName');

Or, Using user model, get the single column value

 $groupName = User::where('username', $username)->pluck('groupName');

Or, get the first row and then split for getting single column value

 $data = User::where('username', $username)->first();

c# dictionary How to add multiple values for single key?

Though nearly the same as most of the other responses, I think this is the most efficient and concise way to implement it. Using TryGetValue is faster than using ContainsKey and reindexing into the dictionary as some other solutions have shown.

void Add(string key, string val)
    List<string> list;

    if (!dictionary.TryGetValue(someKey, out list))
       values = new List<string>();
       dictionary.Add(key, list);


select2 - hiding the search box

try this CSS

  display: none;

this input is search field

Java Garbage Collection Log messages

Most of it is explained in the GC Tuning Guide (which you would do well to read anyway).

The command line option -verbose:gc causes information about the heap and garbage collection to be printed at each collection. For example, here is output from a large server application:

[GC 325407K->83000K(776768K), 0.2300771 secs]
[GC 325816K->83372K(776768K), 0.2454258 secs]
[Full GC 267628K->83769K(776768K), 1.8479984 secs]

Here we see two minor collections followed by one major collection. The numbers before and after the arrow (e.g., 325407K->83000K from the first line) indicate the combined size of live objects before and after garbage collection, respectively. After minor collections the size includes some objects that are garbage (no longer alive) but that cannot be reclaimed. These objects are either contained in the tenured generation, or referenced from the tenured or permanent generations.

The next number in parentheses (e.g., (776768K) again from the first line) is the committed size of the heap: the amount of space usable for java objects without requesting more memory from the operating system. Note that this number does not include one of the survivor spaces, since only one can be used at any given time, and also does not include the permanent generation, which holds metadata used by the virtual machine.

The last item on the line (e.g., 0.2300771 secs) indicates the time taken to perform the collection; in this case approximately a quarter of a second.

The format for the major collection in the third line is similar.

The format of the output produced by -verbose:gc is subject to change in future releases.

I'm not certain why there's a PSYoungGen in yours; did you change the garbage collector?

Room - Schema export directory is not provided to the annotation processor so we cannot export the schema

As per the docs:

You can set annotation processor argument (room.schemaLocation) to tell Room to export the schema into a folder. Even though it is not mandatory, it is a good practice to have version history in your codebase and you should commit that file into your version control system (but don't ship it with your app!).

So if you don't need to check the schema and you want to get rid of the warning, just add exportSchema = false to your RoomDatabase, as follows.

@Database(entities = { YourEntity.class }, version = 1, exportSchema = false)
public abstract class AppDatabase extends RoomDatabase {

If you follow @mikejonesguy answer below, you will follow the good practice mentioned in the docs :). Basically you will get a .json file in your ../app/schemas/ folder. And it looks something like this:

  "formatVersion": 1,
  "database": {
    "version": 1,
    "identityHash": "53db508c5248423325bd5393a1c88c03",
    "entities": [
        "tableName": "sms_table",
        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT, `message` TEXT, `date` INTEGER, `client_id` INTEGER)",
        "fields": [
            "fieldPath": "id",
            "columnName": "id",
            "affinity": "INTEGER"
            "fieldPath": "message",
            "columnName": "message",
            "affinity": "TEXT"
            "fieldPath": "date",
            "columnName": "date",
            "affinity": "INTEGER"
            "fieldPath": "clientId",
            "columnName": "client_id",
            "affinity": "INTEGER"
        "primaryKey": {
          "columnNames": [
          "autoGenerate": true
        "indices": [],
        "foreignKeys": []
    "setupQueries": [
      "CREATE TABLE IF NOT EXISTS room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)",
      "INSERT OR REPLACE INTO room_master_table (id,identity_hash) VALUES(42, \"53db508c5248423325bd5393a1c88c03\")"

If my understanding is correct, you will get such a file with every database version update, so that you can easily follow the history of your db.

How can I get the current screen orientation?

In case anyone would like to obtain meaningful orientation description (like that passed to onConfigurationChanged(..) with those reverseLandscape, sensorLandscape and so on), simply use getRequestedOrientation()

MySQL > Table doesn't exist. But it does (or it should)

In my case it was SQLCA.DBParm parameter.

I used

SQLCA.DBParm = "Databse = "sle_database.text""

but it must be

SQLCA.DBParm = "Database='" +sle_database.text+ "'"

Explaination :

You are going to combine three strings :

 1. Database='              -  "Database='"

 2. (name of the database)  - +sle_database.text+

 3. '                       - "'" (means " ' "  without space)

Don't use spaces in quatermarks. Thank to my colleague Jan.

TypeError: unhashable type: 'dict'

You're trying to use a dict as a key to another dict or in a set. That does not work because the keys have to be hashable. As a general rule, only immutable objects (strings, integers, floats, frozensets, tuples of immutables) are hashable (though exceptions are possible). So this does not work:

>>> dict_key = {"a": "b"}
>>> some_dict[dict_key] = True
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'dict'

To use a dict as a key you need to turn it into something that may be hashed first. If the dict you wish to use as key consists of only immutable values, you can create a hashable representation of it like this:

>>> key = frozenset(dict_key.items())

Now you may use key as a key in a dict or set:

>>> some_dict[key] = True
>>> some_dict
{frozenset([('a', 'b')]): True}

Of course you need to repeat the exercise whenever you want to look up something using a dict:

>>> some_dict[dict_key]                     # Doesn't work
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'dict'
>>> some_dict[frozenset(dict_key.items())]  # Works

If the dict you wish to use as key has values that are themselves dicts and/or lists, you need to recursively "freeze" the prospective key. Here's a starting point:

def freeze(d):
    if isinstance(d, dict):
        return frozenset((key, freeze(value)) for key, value in d.items())
    elif isinstance(d, list):
        return tuple(freeze(value) for value in d)
    return d

Java: How can I compile an entire directory structure of code ?

With Bash 4+, you can just enable globstar

shopt -s globstar

and then do

javac **/*.java

Passing JavaScript array to PHP through jQuery $.ajax

I know it may be too late to answer this, but this worked for me in a great way:

  1. Stringify your javascript object (json) with var st = JSON.stringify(your_object);

  2. Pass your POST data as "string" (maybe using jQuery: $.post('foo.php',{data:st},function(data){... });

  3. Decode your data on the server-side processing: $data = json_decode($_POST['data']);

That's it... you can freely use your data.

Multi-dimensional arrays and single arrays are handled as normal arrays. To access them just do the normal $foo[4].

Associative arrays (javsacript objects) are handled as php objects (classes). To access them just do it like classes: $foo->bar.

Generate class from database table

I tried to use the suggestions above and in the process improved upon the solutions in this thread.

Let us say you use a base class (ObservableObject in this case) that implements the PropertyChanged Event, you would do something like this. I will probably write a blog post one day in my blog

Please do substitute the values for the first three variables:

    --These three things have to be substituted (when called from Powershell, they are replaced before execution)
DECLARE @Schema VARCHAR(MAX) = N'&Schema'
DECLARE @TableName VARCHAR(MAX) = N'&TableName'
DECLARE @Namespace VARCHAR(MAX) = N'&Namespace'

DECLARE @result VARCHAR(max) = ' '

DECLARE @PrivateProp VARCHAR(100) = @CRLF + 
                CHAR(9) + CHAR(9) + 'private <ColumnType> _<ColumnName>;';
DECLARE @PublicProp VARCHAR(255) = @CRLF + 
                CHAR(9) + CHAR(9) + 'public <ColumnType> <ColumnName> '  + @CRLF +
                CHAR(9) + CHAR(9) + '{ ' + @CRLF +
                CHAR(9) + CHAR(9) + '   get { return _<ColumnName>; } ' + @CRLF +
                CHAR(9) + CHAR(9) + '   set ' + @CRLF +
                CHAR(9) + CHAR(9) + '   { ' + @CRLF +
                CHAR(9) + CHAR(9) + '       _<ColumnName> = value;' + @CRLF +
                CHAR(9) + CHAR(9) + '       base.RaisePropertyChanged();' + @CRLF +
                CHAR(9) + CHAR(9) + '   } ' + @CRLF +
                CHAR(9) + CHAR(9) + '}' + @CRLF;

                CHAR(9) + CHAR(9) + 'public event PropertyChangedEventHandler PropertyChanged; ' + @CRLF +
                CHAR(9) + CHAR(9) + 'private void RaisePropertyChanged( ' + @CRLF +
                CHAR(9) + CHAR(9) + '       [CallerMemberName] string caller = "" ) ' + @CRLF +
                CHAR(9) + CHAR(9) + '{  ' + @CRLF +
                CHAR(9) + CHAR(9) + '   if (PropertyChanged != null)  ' + @CRLF +
                CHAR(9) + CHAR(9) + '   { ' + @CRLF +
                CHAR(9) + CHAR(9) + '       PropertyChanged( this, new PropertyChangedEventArgs( caller ) );  ' + @CRLF +
                CHAR(9) + CHAR(9) + '   } ' + @CRLF +
                CHAR(9) + CHAR(9) + '}';

DECLARE @PropChanged VARCHAR(200) =  @CRLF +            
                CHAR(9) + CHAR(9) + 'protected override void AfterPropertyChanged(string propertyName) ' + @CRLF +
                CHAR(9) + CHAR(9) + '{ ' + @CRLF +
                CHAR(9) + CHAR(9) + '   System.Diagnostics.Debug.WriteLine("' + @TableName + ' property changed: " + propertyName); ' + @CRLF +
                CHAR(9) + CHAR(9) + '}';

SET @result = 'using System;' + @CRLF + @CRLF +
                'using MyCompany.Business;' + @CRLF + @CRLF +
                'namespace ' + @Namespace  + @CRLF + '{' + @CRLF +
                '   public class ' + @TableName + ' : ObservableObject' + @CRLF + 
                '   {' + @CRLF +
                '   #region Instance Properties' + @CRLF 

SELECT @result = @result
                            , '<ColumnName>', ColumnName)
                        , '<ColumnType>', ColumnType)
                            , '<ColumnName>', ColumnName)
                        , '<ColumnType>', ColumnType)                   
    SELECT  c.COLUMN_NAME   AS ColumnName 
        , CASE c.DATA_TYPE   
            WHEN 'bigint' THEN
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Int64?' ELSE 'Int64' END
            WHEN 'binary' THEN 'Byte[]'
            WHEN 'bit' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Boolean?' ELSE 'Boolean' END            
            WHEN 'char' THEN 'String'
            WHEN 'date' THEN
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'DateTime?' ELSE 'DateTime' END                        
            WHEN 'datetime' THEN
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'DateTime?' ELSE 'DateTime' END                        
            WHEN 'datetime2' THEN  
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'DateTime?' ELSE 'DateTime' END                        
            WHEN 'datetimeoffset' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'DateTimeOffset?' ELSE 'DateTimeOffset' END                                    
            WHEN 'decimal' THEN  
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Decimal?' ELSE 'Decimal' END                                    
            WHEN 'float' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Single?' ELSE 'Single' END                                    
            WHEN 'image' THEN 'Byte[]'
            WHEN 'int' THEN  
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Int32?' ELSE 'Int32' END
            WHEN 'money' THEN
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Decimal?' ELSE 'Decimal' END                                                
            WHEN 'nchar' THEN 'String'
            WHEN 'ntext' THEN 'String'
            WHEN 'numeric' THEN
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Decimal?' ELSE 'Decimal' END                                                            
            WHEN 'nvarchar' THEN 'String'
            WHEN 'real' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Double?' ELSE 'Double' END                                                                        
            WHEN 'smalldatetime' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'DateTime?' ELSE 'DateTime' END                                    
            WHEN 'smallint' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Int16?' ELSE 'Int16'END            
            WHEN 'smallmoney' THEN  
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Decimal?' ELSE 'Decimal' END                                                                        
            WHEN 'text' THEN 'String'
            WHEN 'time' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'TimeSpan?' ELSE 'TimeSpan' END                                                                                    
            WHEN 'timestamp' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'DateTime?' ELSE 'DateTime' END                                    
            WHEN 'tinyint' THEN 
                CASE C.IS_NULLABLE
                    WHEN 'YES' THEN 'Byte?' ELSE 'Byte' END                                                
            WHEN 'uniqueidentifier' THEN 'Guid'
            WHEN 'varbinary' THEN 'Byte[]'
            WHEN 'varchar' THEN 'String'
            ELSE 'Object'
        END AS ColumnType
WHERE   c.TABLE_NAME = @TableName 
) t

SELECT @result = @result + @CRLF + 
                CHAR(9) + '#endregion Instance Properties' + @CRLF +
                --CHAR(9) + @RPCProc + @CRLF +
                CHAR(9) + @PropChanged + @CRLF +
                CHAR(9) + '}' + @CRLF +
                @CRLF + '}' 
--SELECT @result
PRINT @result

The base class is based on Josh Smith's article here From

I did rename the class to be called ObservableObject and also took advantage of a c# 5 feature using the CallerMemberName attribute

//Jana's change: Used c# 5 feature to bypass passing in the property name using [CallerMemberName] 
//  protected void RaisePropertyChanged([CallerMemberName] string propertyName = "")

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Reflection;
using System.Runtime.CompilerServices;

namespace MyCompany.Business

    /// <summary>
    /// Implements the INotifyPropertyChanged interface and 
    /// exposes a RaisePropertyChanged method for derived 
    /// classes to raise the PropertyChange event.  The event 
    /// arguments created by this class are cached to prevent 
    /// managed heap fragmentation.
    /// </summary>
    public abstract class ObservableObject : INotifyPropertyChanged
        #region Data

        private static readonly Dictionary<string, PropertyChangedEventArgs> eventArgCache;
        private const string ERROR_MSG = "{0} is not a public property of {1}";

        #endregion // Data

        #region Constructors

        static ObservableObject()
            eventArgCache = new Dictionary<string, PropertyChangedEventArgs>();

        protected ObservableObject()

        #endregion // Constructors

        #region Public Members

        /// <summary>
        /// Raised when a public property of this object is set.
        /// </summary>
        [field: NonSerialized]
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// Returns an instance of PropertyChangedEventArgs for 
        /// the specified property name.
        /// </summary>
        /// <param name="propertyName">
        /// The name of the property to create event args for.
        /// </param>        
        public static PropertyChangedEventArgs
            GetPropertyChangedEventArgs(string propertyName)
            if (String.IsNullOrEmpty(propertyName))
                throw new ArgumentException(
                    "propertyName cannot be null or empty.");

            PropertyChangedEventArgs args;

            // Get the event args from the cache, creating them
            // and adding to the cache if necessary.
            lock (typeof(ObservableObject))
                bool isCached = eventArgCache.ContainsKey(propertyName);
                if (!isCached)
                        new PropertyChangedEventArgs(propertyName));

                args = eventArgCache[propertyName];

            return args;

        #endregion // Public Members

        #region Protected Members

        /// <summary>
        /// Derived classes can override this method to
        /// execute logic after a property is set. The 
        /// base implementation does nothing.
        /// </summary>
        /// <param name="propertyName">
        /// The property which was changed.
        /// </param>
        protected virtual void AfterPropertyChanged(string propertyName)

        /// <summary>
        /// Attempts to raise the PropertyChanged event, and 
        /// invokes the virtual AfterPropertyChanged method, 
        /// regardless of whether the event was raised or not.
        /// </summary>
        /// <param name="propertyName">
        /// The property which was changed.
        /// </param>
        protected void RaisePropertyChanged([CallerMemberName] string propertyName = "")

            PropertyChangedEventHandler handler = this.PropertyChanged;
            if (handler != null)
                // Get the cached event args.
                PropertyChangedEventArgs args =

                // Raise the PropertyChanged event.
                handler(this, args);


        #endregion // Protected Members

        #region Private Helpers

        private void VerifyProperty(string propertyName)
            Type type = this.GetType();

            // Look for a public property with the specified name.
            PropertyInfo propInfo = type.GetProperty(propertyName);

            if (propInfo == null)
                // The property could not be found,
                // so alert the developer of the problem.

                string msg = string.Format(


        #endregion // Private Helpers

Here is the part that you guys are going to like some more. I built a Powershell script to generate for all the tables in a SQL database. It is based on a Powershell guru named Chad Miller's Invoke-SQLCmd2 cmdlet which can be downloaded from here:

Once you have that cmdlet, the Powershell script to generate for all tables becomes simple (do substitute the variables with your specific values).

. C:\MyScripts\Invoke-Sqlcmd2.ps1

$serverInstance = "MySQLInstance"
$databaseName = "MyDb"
$generatorSQLFile = "C:\MyScripts\ModelGen.sql" 
$tableListSQL = "SELECT name FROM $databaseName.sys.tables"
$outputFolder = "C:\MyScripts\Output\"
$namespace = "MyCompany.Business"

$placeHolderSchema = "&Schema"
$placeHolderTableName = "&TableName"
$placeHolderNamespace = "&Namespace"

#Get the list of tables in the database to generate c# models for
$tables = Invoke-Sqlcmd2 -ServerInstance $serverInstance -Database $databaseName -Query $tableListSQL -As DataRow -Verbose

foreach ($table in $tables)
    $table1 = $table[0]
    $outputFile = "$outputFolder\$table1.cs"

    #Replace variables with values (returns an array that we convert to a string to use as query)
    $generatorSQLFileWSubstitutions = (Get-Content $generatorSQLFile).
                                            Replace($placeHolderTableName, $table1).
                                            Replace($placeHolderNamespace, $namespace) | Out-String

    "Ouputing for $table1 to $outputFile"

    #The command generates .cs file content for model using "PRINT" statements which then gets written to verbose output (stream 4)
    # ...capture the verbose output and redirect to a file
    (Invoke-Sqlcmd2 -ServerInstance $serverInstance -Database $databaseName -Query $generatorSQLFileWSubstitutions -Verbose) 4> $outputFile


How to increase maximum execution time in php

ini_set('max_execution_time', '300'); //300 seconds = 5 minutes
ini_set('max_execution_time', '0'); // for infinite time of execution 

Place this at the top of your PHP script and let your script loose!

Taken from Increase PHP Script Execution Time Limit Using ini_set()

Makefile - missing separator

You need to precede the lines starting with gcc and rm with a hard tab. Commands in make rules are required to start with a tab (unless they follow a semicolon on the same line). The result should look like this:

PROG = semsearch
all: $(PROG)
%: %.c
        gcc -o $@ $< -lpthread

        rm $(PROG)

Note that some editors may be configured to insert a sequence of spaces instead of a hard tab. If there are spaces at the start of these lines you'll also see the "missing separator" error. If you do have problems inserting hard tabs, use the semicolon way:

PROG = semsearch
all: $(PROG)
%: %.c ; gcc -o $@ $< -lpthread

clean: ; rm $(PROG)

Converting a character code to char (VB.NET)

The Chr function in VB.NET converts the integer back to the character:

Dim i As Integer = Asc("x") ' Convert to ASCII integer.
Dim x As Char = Chr(i)      ' Convert ASCII integer to char.

Freezing Row 1 and Column A at the same time

Select cell B2 and click "Freeze Panes" this will freeze Row 1 and Column A.

For future reference, selecting Freeze Panes in Excel will freeze the rows above your selected cell and the columns to the left of your selected cell. For example, to freeze rows 1 and 2 and column A, you could select cell B3 and click Freeze Panes. You could also freeze columns A and B and row 1, by selecting cell C2 and clicking "Freeze Panes".

Visual Aid on Freeze Panes in Excel 2010 -

Microsoft Reference Guide (More Complicated, but resourceful none the less) -

import .css file into .less file

If you want to import a css file that should be treaded as less use this line:

.ie {
  @import (less) 'ie.css';

How to input a string from user into environment variable from batch file

A rather roundabout way, just for completeness:

 for /f "delims=" %i in ('type CON') do set inp=%i

Of course that requires ^Z as a terminator, and so the Johannes answer is better in all practical ways.

Adding a directory to the PATH environment variable in Windows

Handy if you are already in the directory you want to add to PATH:

set PATH=%PATH%;%CD%

It works with the standard Windows cmd, but not in PowerShell.

For PowerShell, the %CD% equivalent is [System.Environment]::CurrentDirectory.

Text inset for UITextField?

I did this in IB where I created a UIView Behind the textView that was a little bit longer. With the textField background color set to clear. enter image description here

SQL Server : fetching records between two dates?

The unambiguous way to write this is (i.e. increase the 2nd date by 1 and make it <)

select * 
from xxx 
where dates >= '20121026'
  and dates <  '20121028'

If you're using SQL Server 2008 or above, you can safety CAST as DATE while retaining SARGability, e.g.

select * 
from xxx 
where CAST(dates as DATE) between '20121026' and '20121027'

This explicitly tells SQL Server that you are only interested in the DATE portion of the dates column for comparison against the BETWEEN range.

What is "stdafx.h" used for in Visual Studio?

I just ran into this myself since I'm trying to create myself a bare bones framework but started out by creating a new Win32 Program option in Visual Studio 2017. "stdafx.h" is unnecessary and should be removed. Then you can remove the stupid "stdafx.h" and "stdafx.cpp" that is in your Solution Explorer as well as the files from your project. In it's place, you'll need to put

#include <Windows.h>


Variable interpolation in the shell

In Bash:

tail -1 ${filepath}

MySQL Foreign Key Error 1005 errno 150 primary key as foreign key

MySQL is notoriously cranky, especially with regards to foreign keys and triggers. I am right now in the process of fine tuning one such database, and ran into this problem. It is not self evident or intuitive, so here it goes:

Besides checking if the two columns you want to reference in the relationship have the same data type, you must also make sure the column on the table you are referencing is an index. If you are using the MySQL Workbench, select the tab "Indexes" right next to "Columns" and make sure the column referenced by the foreign key is an index. If not, create one, name it something meaningful, and give it the type "INDEX".

A good practice is to clean up the tables involved in relationships to make sure previous attempts did not create indexes you don't want or need.

I hope it helped, some MySQL errors are maddening to track.

Accessing clicked element in angularjs

While AngularJS allows you to get a hand on a click event (and thus a target of it) with the following syntax (note the $event argument to the setMaster function; documentation here:

function AdminController($scope) {    
  $scope.setMaster = function(obj, $event){

this is not very angular-way of solving this problem. With AngularJS the focus is on the model manipulation. One would mutate a model and let AngularJS figure out rendering.

The AngularJS-way of solving this problem (without using jQuery and without the need to pass the $event argument) would be:

<div ng-controller="AdminController">
    <ul class="list-holder">
        <li ng-repeat="section in sections" ng-class="{active : isSelected(section)}">
            <a ng-click="setMaster(section)">{{}}</a>
    {{selected | json}}

where methods in the controller would look like this:

$scope.setMaster = function(section) {
    $scope.selected = section;

$scope.isSelected = function(section) {
    return $scope.selected === section;

Here is the complete jsFiddle:

How to change the project in GCP using CLI commands

Make sure you are authenticated with the correct account:

gcloud auth list
* account 1
  account 2

Change to the project's account if not:

gcloud config set account `ACCOUNT`

Depending on the account, the project list will be different:

gcloud projects list

- project 1
- project 2...

Switch to intended project:

gcloud config set project `PROJECT ID`

How to read the RGB value of a given pixel in Python?

As Dave Webb said:

Here is my working code snippet printing the pixel colours from an image:

import os, sys
import Image

im ="image.jpg")
x = 3
y = 4

pix = im.load()
print pix[x,y]

What is the purpose of "pip install --user ..."?

Just a warning:

According to this issue, --user is currently not valid inside a virtual env's pip, since a user location doesn't really make sense for a virtual environment.

So do not use pip install --user some_pkg inside a virtual environment, otherwise, virtual environment's pip will be confused. See this answer for more details.

PHP compare two arrays and get the matched values not the difference

OK.. We needed to compare a dynamic number of product names...

There's probably a better way... but this works for me...

... because....Strings are just Arrays of characters.... :>}

//  Compare Strings ...  Return Matching Text and Differences with Product IDs...

//  From MySql...
$productID1 = 'abc123';
$productName1 = "EcoPlus Premio Jet 600";   

$productID2 = 'xyz789';
$productName2 = "EcoPlus Premio Jet 800";   

$ProductNames = array(
    $productID1 => $productName1,
    $productID2 => $productName2

function compareNames($ProductNames){   

    //  Convert NameStrings to Arrays...    
    foreach($ProductNames as $id => $product_name){
        $Package1[$id] = explode(" ",$product_name);    

    // Get Matching Text...
    $Matching = call_user_func_array('array_intersect', $Package1 );
    $MatchingText = implode(" ",$Matching);

    //  Get Different Text...
    foreach($Package1 as $id => $product_name_chunks){
        $Package2 = array($product_name_chunks,$Matching);
        $diff = call_user_func_array('array_diff', $Package2 );
        $DifferentText[$id] = trim(implode(" ", $diff));

    $results[$MatchingText]  = $DifferentText;              
    return $results;    

$Results =  compareNames($ProductNames);


// Gives us this...
[EcoPlus Premio Jet] 
        [abc123] => 600
        [xyz789] => 800

newline in <td title="">

I use the jQuery clueTip plugin for this.

UIButton Image + Text IOS

You should create custom imageview for image and custom label for text and you add to your button as subviews. That's it.

UIButton *yourButton = [UIButton buttonWithType:UIButtonTypeCustom];
yourButton.backgroundColor = [UIColor greenColor];
yourButton.frame = CGRectMake(140, 40, 175, 30);     
[yourButton addTarget:self action:@selector(yourButtonSelected:) forControlEvents:UIControlEventTouchUpInside]; 
[self.view addSubview:yourButton];

UIImageView *imageView1 = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, yourButton.frame.size.width, yourButton.frame.size.height/2)];
imageView1.image =[UIImage imageNamed:@"images.jpg"];
[yourButton addSubview:imageView1];

UILabel *label=[[UILabel alloc] initWithFrame:CGRectMake(0, yourButton.frame.size.height/2, yourButton.frame.size.width, yourButton.frame.size.height/2)];
label.backgroundColor = [UIColor greenColor];
label.textAlignment= UITextAlignmentCenter;
label.text = @"ButtonTitle";
[yourButton addSubview:label];

For testing purpose, use yourButtonSelected: method

    NSLog(@"Your Button Selected");


I think it will be helpful to you.

Google Play Services GCM 9.2.0 asks to "update" back to 9.0.0

The same situation was with the previous versions. It's annoing that new versions libraries are always releasing before plugin, and it's impossible to use new version because is incompatible with old plugin. I don't know if plugin is now required (google docs sucks). I remember times when it wasn't. The only way is wait for new plugin version, or you can try to remove plugin dependencies, but as I said I'am not sure if gcm will work without it. What I know the main feature of 9.2.0 version is new Awareness API, if you didn't need it, you can use 9.0.0 version without any trouble.

How get data from material-ui TextField, DropDownMenu components?

Here all solutions are based on Class Component, but i guess most of the people who learned React recently (like me), at this time using functional Component. So here is the solution based on functional component.

Using useRef hooks of ReactJs and inputRef property of TextField.

    import React, { useRef, Component } from 'react'
    import { TextField, Button } from '@material-ui/core'
    import SendIcon from '@material-ui/icons/Send'

    export default function MultilineTextFields() {
    const valueRef = useRef('') //creating a refernce for TextField Component

    const sendValue = () => {
        return console.log(valueRef.current.value) //on clicking button accesing current value of TextField and outputing it to console 

    return (
        <form noValidate autoComplete='off'>
            placeholder='Write your thoughts'
            inputRef={valueRef}   //connecting inputRef property of TextField to the valueRef
            endIcon={<SendIcon />}

Curl GET request with json parameter

This should work :

  curl -i -H "Accept: application/json" 'server:5050/a/c/getName{"param0":"pradeep"}'

use option -i instead of x.

How do I get the old value of a changed cell in Excel VBA?

Here's a way I've used in the past. Please note that you have to add a reference to the Microsoft Scripting Runtime so you can use the Dictionary object - if you don't want to add that reference you can do this with Collections but they're slower and there's no elegant way to check .Exists (you have to trap the error).

Dim OldVals As New Dictionary
Private Sub Worksheet_Change(ByVal Target As Range)
Dim cell As Range
    For Each cell In Target
        If OldVals.Exists(cell.Address) Then
            Debug.Print "New value of " & cell.Address & " is " & cell.Value & "; old value was " & OldVals(cell.Address)
            Debug.Print "No old value for " + cell.Address
        End If
        OldVals(cell.Address) = cell.Value
End Sub

Like any similar method, this has its problems - first off, it won't know the "old" value until the value has actually been changed. To fix this you'd need to trap the Open event on the workbook and go through Sheet.UsedRange populating OldVals. Also, it will lose all its data if you reset the VBA project by stopping the debugger or some such.

How to get a cross-origin resource sharing (CORS) post request working


            url: "http://localhost:8079/students/add/",
            type: "POST",
            crossDomain: true,
            data: JSON.stringify(somejson),
            dataType: "json",
            success: function (response) {
                var resp = JSON.parse(response)
            error: function (xhr, status) {


response = HttpResponse(json.dumps('{"status" : "success"}'))
response.__setitem__("Content-type", "application/json")
response.__setitem__("Access-Control-Allow-Origin", "*")

return response

How to fix Python Numpy/Pandas installation?

Don't know if you solved the problem but if anyone has this problem in future.

>>import numpy

Go to the location printed and delete the numpy installation found there. You can then use pip or easy_install

Mysql select distinct

You can use DISTINCT like that

mysql_query("SELECT DISTINCT(ticket_id), column1, column2, column3 
FROM temp_tickets 
ORDER BY ticket_id");

Python, HTTPS GET with basic authentication

Based on the @AndrewCox 's answer with some minor improvements:

from http.client import HTTPSConnection
from base64 import b64encode

client = HTTPSConnection("")
user = "user_name"
password = "password"
headers = {
    "Authorization": "Basic {}".format(
        b64encode(bytes(f"{user}:{password}", "utf-8")).decode("ascii")
client.request('GET', '/', headers=headers)
res = client.getresponse()
data =

Note, you should set encoding if you use bytes function instead of b"".

How to print the current time in a Batch-File?

This works with Windows 10, 8.x, 7, and possibly further back:

@echo Started: %date% %time%
@echo Completed: %date% %time%

Setting focus on an HTML input box on page load

This is one of the common issues with IE and fix for this is simple. Add .focus() twice to the input.

Fix :-

function FocusOnInput() {
    var element = document.getElementById('txtContactMobileNo');
    setTimeout(function () { element.focus(); }, 1);

And call FocusOnInput() on $(document).ready(function () {.....};

Programmatically navigate using react router V4

I had a similar issue when migrating over to React-Router v4 so I'll try to explain my solution below.

Please do not consider this answer as the right way to solve the problem, I imagine there's a good chance something better will arise as React Router v4 becomes more mature and leaves beta (It may even already exist and I just didn't discover it).

For context, I had this problem because I occasionally use Redux-Saga to programmatically change the history object (say when a user successfully authenticates).

In the React Router docs, take a look at the <Router> component and you can see you have the ability to pass your own history object via a prop. This is the essence of the solution - we supply the history object to React-Router from a global module.


  1. Install the history npm module - yarn add history or npm install history --save
  2. create a file called history.js in your App.js level folder (this was my preference)

    // src/history.js
    import createHistory from 'history/createBrowserHistory';
    export default createHistory();`
  3. Add this history object to your Router component like so

    // src/App.js
    import history from '../your/path/to/history.js;'
    <Router history={history}>
    // Route tags here
  4. Adjust the URL just like before by importing your global history object:

    import history from '../your/path/to/history.js;'

Everything should stay synced up now, and you also have access to a way of setting the history object programmatically and not via a component/container.

How can I check if a var is a string in JavaScript?

Now days I believe it's preferred to use a function form of typeof() so...

if(filename === undefined || typeof(filename) !== "string" || filename === "") {
   console.log("no filename aborted.");

How do I pull from a Git repository through an HTTP proxy?

I had the same problem, with a slightly different fix: REBUILDING GIT WITH HTTP SUPPORT

The git: protocol did not work through my corporate firewall.

For example, this timed out:

git clone git://

curl works just fine, though, so I know my http_proxy environment variable is correct.

I tried using http, like below, but got an immediate error.

git clone

->>>  fatal: Unable to find remote helper for 'http' <<<-

I tried recompiling git like so:

./configure  --with-curl --with-expat

but still got the fatal error.

Finally, after several frustrating hours, I read the configure file, and saw this:

# Define CURLDIR=/foo/bar if your curl header and library files are in

# /foo/bar/include and /foo/bar/lib directories.

I remembered then, that I had not complied curl from source, and so went looking for the header files. Sure enough, they were not installed. That was the problem. Make did not complain about the missing header files. So I did not realize that the --with-curl option did nothing (it is, in fact the default in my version of git).

I did the following to fix it:

  1. Added the headers needed for make:

    yum install curl-devel
    (expat-devel-1.95.8-8.3.el5_5.3.i386  was already installed).
  2. Removed git from /usr/local (as I want the new install to live there).

    I simply removed git* from /usr/local/share and /usr/local/libexec

  3. Searched for the include dirs containing the curl and expat header files, and then (because I had read through configure) added these to the environment like so:

    export CURLDIR=/usr/include 
    export EXPATDIR=/usr/include
  4. Ran configure with the following options, which, again, were described in the configure file itself, and were also the defaults but what the heck:

    ./configure  --with-curl --with-expat
  5. And now http works with git through my corporate firewall:

    git clone
    Cloning into 'node-websocket-server'...
    * Couldn't find host in the .netrc file, using defaults
    * About to connect() to proxy port 8080
    *   Trying * connected

How to set ChartJS Y axis title?

For Chart.js 2.x refer to andyhasit's answer -

For Chart.js 1.x, you can tweak the options and extend the chart type to do this, like so

    name: "LineAlt",
    draw: function () {
        Chart.types.Line.prototype.draw.apply(this, arguments);

        var ctx = this.chart.ctx;;
        // text alignment and color
        ctx.textAlign = "center";
        ctx.textBaseline = "bottom";
        ctx.fillStyle = this.options.scaleFontColor;
        // position
        var x = this.scale.xScalePaddingLeft * 0.4;
        var y = this.chart.height / 2;
        // change origin
        ctx.translate(x, y);
        // rotate text
        ctx.rotate(-90 * Math.PI / 180);
        ctx.fillText(this.datasets[0].label, 0, 0);

calling it like this

var ctx = document.getElementById("myChart").getContext("2d");
var myLineChart = new Chart(ctx).LineAlt(data, {
    // make enough space on the right side of the graph
    scaleLabel: "          <%=value%>"

Notice the space preceding the label value, this gives us space to write the y axis label without messing around with too much of Chart.js internals

Fiddle -

enter image description here

iOS 7: UITableView shows under status bar

If you also need to support iOS 6, you'll have to conditionally move it down. That is, in iOS 7 you should just move it down 20 points (either through frame manipulation or using auto-layout), and in iOS 6 you leave it alone. I don't believe you can do this in IB, so you'll have to do it in code.


You can actually do this in IB, by using the iOS6/iOS7 deltas. Set your position in iOS 7, then for iOS 6 set the delta Y to -20points. See this SO question for more information.

Select box arrow style

The select box arrow is a native ui element, it depends on the desktop theme or the web browser. Use a jQuery plugin (e.g. Select2, Chosen) or CSS.

AngularJS - Passing data between pages

What you should do is create a service to share data between controllers.

Nice tutorial

Remove numbers from string sql server

Remove everything after first digit (was adequate for my use case): LEFT(field,PATINDEX('%[0-9]%',field+'0')-1)

Remove trailing digits: LEFT(field,len(field)+1-PATINDEX('%[^0-9]%',reverse('0'+field))

Specifying java version in maven - differences between properties and compiler plugin

Consider the alternative:


It should be the same thing of maven.compiler.source/ but the above solution works for me, otherwise the second one gets the parent specification (I have a matrioska of .pom)

ipad safari: disable scrolling, and bounce effect?

Code to To remove ipad safari: disable scrolling, and bounce effect

   document.addEventListener("touchmove", function (e) {
    }, { passive: false });

If you have canvas tag inside document, sometime it will affect the usability of object inside Canvas(example: movement of object); so add below code to fix it.

    document.getElementById("canvasId").addEventListener("touchmove", function (e) {
    }, { passive: false });

PHP new line break in emails

Are you building this string using single or double quotes? \r and \n only work with double quotes, as well as embedded variables. For example:

$foo = 'bar';
echo 'Hello \n $foo!';

will output:

Hello \n $foo!


$foo = 'bar';
echo "Hello \n $foo!";

will output:


Calling Oracle stored procedure from C#?

This Code works well for me calling oracle stored procedure

Add references by right clicking on your project name in solution explorer >Add Reference >.Net then Add namespaces.

using System.Data.OracleClient;
using System.Data;

then paste this code in event Handler

        string str = "User ID=username;Password=password;Data Source=Test";
        OracleConnection conn = new OracleConnection(str);
        OracleCommand cmd = new OracleCommand("stored_procedure_name", conn);
        cmd.CommandType = CommandType.StoredProcedure;
        --Ad parameter list--
        cmd.Parameters.Add("parameter_name", "varchar2").Value = value;

And its Done...Happy Coding with C#

How to make Visual Studio copy a DLL file to the output directory?

Add builtin COPY in project.csproj file:

    <Target Name="AfterBuild">
      <Copy SourceFiles="$(ProjectDir)..\..\Lib\*.dll" DestinationFolder="$(OutDir)Debug\bin" SkipUnchangedFiles="false" />
      <Copy SourceFiles="$(ProjectDir)..\..\Lib\*.dll" DestinationFolder="$(OutDir)Release\bin" SkipUnchangedFiles="false" />

How do I assert an Iterable contains elements with a certain property?

As long as your List is a concrete class, you can simply call the contains() method as long as you have implemented your equals() method on MyItem.

// given 
// some input ... you to complete

// when
List<MyItems> results = service.getMyItems();

// then
assertTrue(results.contains(new MyItem("foo")));
assertTrue(results.contains(new MyItem("bar")));

Assumes you have implemented a constructor that accepts the values you want to assert on. I realise this isn't on a single line, but it's useful to know which value is missing rather than checking both at once.

How to suppress Pandas Future warning ?

Warnings are annoying. As mentioned in other answers, you can suppress them using:

import warnings
warnings.simplefilter(action='ignore', category=FutureWarning)

But if you want to handle them one by one and you are managing a bigger codebase, it will be difficult to find the line of code which is causing the warning. Since warnings unlike errors don't come with code traceback. In order to trace warnings like errors, you can write this at the top of the code:

import warnings

But if the codebase is bigger and it is importing bunch of other libraries/packages, then all sort of warnings will start to be raised as errors. In order to raise only certain type of warnings (in your case, its FutureWarning) as error, you can write:

import warnings
warnings.simplefilter(action='error', category=FutureWarning)

Rails: How can I rename a database column in a Ruby on Rails migration?

From API:

rename_column(table_name, column_name, new_column_name)

It renames a column but keeps the type and content remains same.

How to setup FTP on xampp

XAMPP for linux and mac comes with ProFTPD. Make sure to start the service from XAMPP control panel -> manage servers.

Further complete instructions can be found at localhost XAMPP dashboard -> How-to guides -> Configure FTP Access. I have pasted them below :

  1. Open a new Linux terminal and ensure you are logged in as root.

  2. Create a new group named ftp. This group will contain those user accounts allowed to upload files via FTP.

groupadd ftp

  1. Add your account (in this example, susan) to the new group. Add other users if needed.

usermod -a -G ftp susan

  1. Change the ownership and permissions of the htdocs/ subdirectory of the XAMPP installation directory (typically, /opt/lampp) so that it is writable by the the new ftp group.

cd /opt/lampp chown root.ftp htdocs chmod 775 htdocs

  1. Ensure that proFTPD is running in the XAMPP control panel.

You can now transfer files to the XAMPP server using the steps below:

  1. Start an FTP client like winSCP or FileZilla and enter connection details as below.

If you’re connecting to the server from the same system, use "" as the host address. If you’re connecting from a different system, use the network hostname or IP address of the XAMPP server.

Use "21" as the port.

Enter your Linux username and password as your FTP credentials.

Your FTP client should now connect to the server and enter the /opt/lampp/htdocs/ directory, which is the default Web server document root.

  1. Transfer the file from your home directory to the server using normal FTP transfer conventions. If you’re using a graphical FTP client, you can usually drag and drop the file from one directory to the other. If you’re using a command-line FTP client, you can use the FTP PUT command.

Once the file is successfully transferred, you should be able to see it in action.

Git push hangs when pushing to Github?

I just wanted to say that I'm having this issue on my AWS EC2 instances. I was trying to push from my EC2 instance itself, when I have it configured to only allow traffic in from the load balancer. I changed the rule to allow HTTP in from everywhere, but it still didn't fix the problem. Then I realized it's because my security groups are configured to not allow outbound traffic from my EC2 instances over HTTPS. I didn't have allow HTTPS inbound traffic to make it work, even though it's probably a good policy for you to have HTTPS available inbound.

"The semaphore timeout period has expired" error for USB connection

Too many big files all in one go. Windows barfs. Essentially the copying took too long because you asked too much of the computer and the file locking was locked too long and set a flag off, the flag is a semaphore error.

The computer stuffed itself and choked on it. I saw the RAM memory here get progressively filled with a Cache in RAM. Then when filled the subsystem ground to a halt with a semaphore error.

I have a workaround; copy or transfer fewer files not one humongous block. Break it down into sets of blocks and send across the files one at a time, maybe a few at a time, but not never the lot.


JQuery Number Formatting

Browser development progresses:


 // E.g.

SQL Server reports 'Invalid column name', but the column is present and the query works through management studio

In my case I restart Microsoft SQL Sever Management Studio and this works well for me.

Difference in Months between two dates in JavaScript

Sometimes you may want to get just the quantity of the months between two dates totally ignoring the day part. So for instance, if you had two dates- 2013/06/21 and 2013/10/18- and you only cared about the 2013/06 and 2013/10 parts, here are the scenarios and possible solutions:

var date1=new Date(2013,5,21);//Remember, months are 0 based in JS
var date2=new Date(2013,9,18);
var year1=date1.getFullYear();
var year2=date2.getFullYear();
var month1=date1.getMonth();
var month2=date2.getMonth();
if(month1===0){ //Have to take into account
var numberOfMonths; 

1.If you want just the number of the months between the two dates excluding both month1 and month2

numberOfMonths = (year2 - year1) * 12 + (month2 - month1) - 1;

2.If you want to include either of the months

numberOfMonths = (year2 - year1) * 12 + (month2 - month1);

3.If you want to include both of the months

numberOfMonths = (year2 - year1) * 12 + (month2 - month1) + 1;

Slide up/down effect with ng-show and ng-animate

I've written an Angular directive that does slideToggle() without jQuery.

SignalR - Sending a message to a specific user using (IUserIdProvider) *NEW 2.0.0*

Look at SignalR Tests for the feature.

Test "SendToUser" takes automatically the user identity passed by using a regular owin authentication library.

The scenario is you have a user who has connected from multiple devices/browsers and you want to push a message to all his active connections.

Is there a simple way that I can sort characters in a string in alphabetical order

You can use this

string x = "ABCGH"

char[] charX = x.ToCharArray();


This will sort your string.

Android - styling seek bar

As mention one above (@andrew) , creating custom SeekBar is super Easy with this site -

Just enable SeekBar there, choose color, and receive all resources and copy to project. Then apply them in xml, for example:


Correct way to initialize empty slice

They are equivalent. See this code:

mySlice1 := make([]int, 0)
mySlice2 := []int{}
fmt.Println("mySlice1", cap(mySlice1))
fmt.Println("mySlice2", cap(mySlice2))


mySlice1 0
mySlice2 0

Both slices have 0 capacity which implies both slices have 0 length (cannot be greater than the capacity) which implies both slices have no elements. This means the 2 slices are identical in every aspect.

See similar questions:

What is the point of having nil slice and empty slice in golang?

nil slices vs non-nil slices vs empty slices in Go language

How to access form methods and controls from a class in C#?

I'm relatively new to c# and brand new to stackoverflow. Anyway, regarding the question on how to access controls on a form from a class: I just used the ControlCollection (Controls) class of the form.

        //Add a new form called frmEditData to project.
        //Draw a textbox on it named txtTest; set the text to
        //something in design as a test.
        Form frmED =  new frmEditData();

Worked for me, maybe it will be of assistance in both questions.

Calling async method synchronously


Task has Wait method, Task.Wait(), which waits for the "promise" to resolve and then continues, thus rendering it synchronous. example:

async Task<String> MyAsyncMethod() { ... }

String mySyncMethod() {

    return MyAsyncMethod().Wait();

GridLayout and Row/Column Span Woe

You have to set both layout_gravity and layout_columntWeight on your columns


    <TextView android:text="??? ???"

    <TextView android:text="??? ???"

    <TextView android:text="??? ???"

jQuery: Handle fallback for failed AJAX Request

Yes, it's built in to jQuery. See the docs at jquery documentation.

ajaxError may be what you want.

how to send an array in url request

Separate with commas:






Either way, your method signature needs to be:

@RequestMapping(value = "/GetJson", method = RequestMethod.GET) 
public void getJson(@RequestParam("name") String[] ticker, @RequestParam("startDate") String startDate, @RequestParam("endDate") String endDate) {
   //code to get results from db for those params.

How to set up a squid Proxy with basic username and password authentication?

Here's what I had to do to setup basic auth on Ubuntu 14.04 (didn't find a guide anywhere else)

Basic squid conf

/etc/squid3/squid.conf instead of the super bloated default config file

auth_param basic program /usr/lib/squid3/basic_ncsa_auth /etc/squid3/passwords
auth_param basic realm proxy
acl authenticated proxy_auth REQUIRED
http_access allow authenticated

# Choose the port you want. Below we set it to default 3128.
http_port 3128

Please note the basic_ncsa_auth program instead of the old ncsa_auth

squid 2.x

For squid 2.x you need to edit /etc/squid/squid.conf file and place:

auth_param basic program /usr/lib/squid/digest_pw_auth /etc/squid/passwords
auth_param basic realm proxy
acl authenticated proxy_auth REQUIRED
http_access allow authenticated

Setting up a user

sudo htpasswd -c /etc/squid3/passwords username_you_like

and enter a password twice for the chosen username then

sudo service squid3 restart

squid 2.x

sudo htpasswd -c /etc/squid/passwords username_you_like

and enter a password twice for the chosen username then

sudo service squid restart

htdigest vs htpasswd

For the many people that asked me: the 2 tools produce different file formats:

  • htdigest stores the password in plain text.
  • htpasswd stores the password hashed (various hashing algos are available)

Despite this difference in format basic_ncsa_auth will still be able to parse a password file generated with htdigest. Hence you can alternatively use:

sudo htdigest -c /etc/squid3/passwords realm_you_like username_you_like

Beware that this approach is empirical, undocumented and may not be supported by future versions of Squid.

On Ubuntu 14.04 htdigest and htpasswd are both available in the [apache2-utils][1] package.


Similar as above applies, but file paths are different.

Install squid

brew install squid

Start squid service

brew services start squid

Squid config file is stored at /usr/local/etc/squid.conf.

Comment or remove following line:

http_access allow localnet

Then similar to linux config (but with updated paths) add this:

auth_param basic program /usr/local/Cellar/squid/4.8/libexec/basic_ncsa_auth /usr/local/etc/squid_passwords
auth_param basic realm proxy
acl authenticated proxy_auth REQUIRED
http_access allow authenticated

Note that path to basic_ncsa_auth may be different since it depends on installed version when using brew, you can verify this with ls /usr/local/Cellar/squid/. Also note that you should add the above just bellow the following section:


Now generate yourself a user:password basic auth credential (note: htpasswd and htdigest are also both available on MacOS)

htpasswd -c /usr/local/etc/squid_passwords username_you_like

Restart the squid service

brew services restart squid

Fit Image into PictureBox

You could try changing the: SizeMode property of the PictureBox.

You could also set your image as the BackGroundImage of the PictureBox and try changing the BackGroundImageLayout to the correct mode.

ASP.NET Core Get Json Array using IConfiguration

This worked for me to return an array of strings from my config:

var allowedMethods = Configuration.GetSection("AppSettings:CORS-Settings:Allow-Methods")

My configuration section looks like this:

"AppSettings": {
    "CORS-Settings": {
        "Allow-Origins": [ "http://localhost:8000" ],
        "Allow-Methods": [ "OPTIONS","GET","HEAD","POST","PUT","DELETE" ]
} /storage/emulated/0/New file.txt: open failed: EACCES (Permission denied)

For SDK 29 :

String str1 = "";
folder1 = new File(String.valueOf(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES)));
if (folder1.exists()) {str1 = folder1.toString() + File.separator;}

public static void createTextFile(String sBody, String FileName, String Where) {
    try {
        File gpxfile = new File(Where, FileName);
        FileWriter writer = new FileWriter(gpxfile);
    } catch (IOException e) {

Then you can save your file like this :

createTextFile("This is Content","file.txt",str1);

What is a PDB file?

I had originally asked myself the question "Do I need a PDB file deployed to my customer's machine?", and after reading this post, decided to exclude the file.

Everything worked fine, until today, when I was trying to figure out why a message box containing an Exception.StackTrace was missing the file and line number information - necessary for troubleshooting the exception. I re-read this post and found the key nugget of information: that although the PDB is not necessary for the app to run, it is necessary for the file and line numbers to be present in the StackTrace string. I included the PDB file in the executable folder and now all is fine.

iPad/iPhone hover problem causes the user to double click a link

What worked for me is what others here have already said:

Don't show/hide elements on hover or mousemove (which is the event in my case).

Here's what Apple says (

A clickable element is a link, form element, image map area, or any other element with mousemove, mousedown, mouseup, or onclick handlers

If the user taps a clickable element, events arrive in this order: mouseover, mousemove, mousedown, mouseup, and click. Also, if the contents of the page changes on the mousemove event, no subsequent events in the sequence are sent. This behavior allows the user to tap in the new content.

So, you could use @woop's solution: detect the userAgent, check if it's and iOS device and then bind the event. I ended up using this technique because it suits my needs and it makes more sense do not bind hover events when you don't want it.

But... if you don't wanna mess with userAgents and still hide/show elements on hover/mousemove, i found out you can do so by using native javascript, like this:

$("body").on("mouseover", function() {
       document.getElementsByTagName("my-class")[0].style.display = 'block'; //show element
       document.querySelector(".my-selector div").style.display = 'none'; // hide element

This will work on the Desktop version and will do nothing on the mobile version.

And for a little more compatibility...

$("body").on("mouseover", function() {
   if (document.getElementsByTagName && document.querySelector) { // check compatibility
       document.getElementsByTagName("my-class")[0].style.display = 'block'; //show element
       document.querySelector(".my-selector div").style.display = 'none'; // hide element
    } else {
        $(".my-selector div").hide();

Why is @font-face throwing a 404 error on woff files?

Solution for IIS7

I also came across the same issue. I think doing this configuration from the server level would be better since it applies for all the websites.

  1. Go to IIS root node and double-click the "MIME Types" configuration option

  2. Click "Add" link in the Actions panel on the top right.

  3. This will bring up a dialog. Add .woff file extension and specify "application/x-font-woff" as the corresponding MIME type.

Add MIME Type for .woff file name extension

Go to MIME Types

Add MIME Type

Here is what I did to solve the issue in IIS 7

How to deal with the URISyntaxException

Coudn't imagine nothing better for ? ????????????&descr=????????&objectid=2231

public static boolean checkForExternal(String str) {
    int length = str.length();
    for (int i = 0; i < length; i++) {
        if (str.charAt(i) > 0x7F) {
            return true;
    return false;

private static final Pattern COLON = Pattern.compile("%3A", Pattern.LITERAL);
private static final Pattern SLASH = Pattern.compile("%2F", Pattern.LITERAL);
private static final Pattern QUEST_MARK = Pattern.compile("%3F", Pattern.LITERAL);
private static final Pattern EQUAL = Pattern.compile("%3D", Pattern.LITERAL);
private static final Pattern AMP = Pattern.compile("%26", Pattern.LITERAL);

public static String encodeUrl(String url) {
    if (checkForExternal(url)) {
        try {
            String value = URLEncoder.encode(url, "UTF-8");
            value = COLON.matcher(value).replaceAll(":");
            value = SLASH.matcher(value).replaceAll("/");
            value = QUEST_MARK.matcher(value).replaceAll("?");
            value = EQUAL.matcher(value).replaceAll("=");
            return AMP.matcher(value).replaceAll("&");
        } catch (UnsupportedEncodingException e) {
            throw LOGGER.getIllegalStateException(e);
    } else {
        return url;

Checkbox Check Event Listener

Since I don't see the jQuery tag in the OP, here is a javascript only option :

document.addEventListener("DOMContentLoaded", function (event) {
    var _selector = document.querySelector('input[name=myCheckbox]');
    _selector.addEventListener('change', function (event) {
        if (_selector.checked) {
            // do something if checked
        } else {
            // do something else otherwise


Definition of a Balanced Tree

There are several ways to define "Balanced". The main goal is to keep the depths of all nodes to be O(log(n)).

It appears to me that the balance condition you were talking about is for AVL tree.
Here is the formal definition of AVL tree's balance condition:

For any node in AVL, the height of its left subtree differs by at most 1 from the height of its right subtree.

Next question, what is "height"?

The "height" of a node in a binary tree is the length of the longest path from that node to a leaf.

There is one weird but common case:

People define the height of an empty tree to be (-1).

For example, root's left child is null:

              A  (Height = 2)
           /     \
(height =-1)       B (Height = 1) <-- Unbalanced because 1-(-1)=2 >1
                     C (Height = 0)

Two more examples to determine:

Yes, A Balanced Tree Example:

        A (h=3)
     /     \
 B(h=1)     C (h=2)        
/          /   \
D (h=0)  E(h=0)  F (h=1)
              G (h=0)

No, Not A Balanced Tree Example:

        A (h=3)
     /     \
 B(h=0)     C (h=2)        <-- Unbalanced: 2-0 =2 > 1
           /   \
        E(h=1)  F (h=0)
        /     \
      H (h=0)   G (h=0)      

Making a div vertically scrollable using CSS

For 100% viewport height use:

overflow: auto;
max-height: 100vh;

HAProxy redirecting http to https (ssl)

redirect statement is legacy

use http-request redirect instead

acl http      ssl_fc,not
http-request redirect scheme https if http

Filename too long in Git for Windows

I had this error too, but in my case the cause was using an outdated version of npm, v1.4.28.

Updating to npm v3 followed by

rm -rf node_modules
npm -i

worked for me. npm issue 2697 has details of the "maximally flat" folder structure included in npm v3 (released 2015-06-25).

How to find rows in one table that have no corresponding row in another table

select from parentTable
left outer join childTable on ( = childTable.parentTableID) 
where is null

How to check undefined in Typescript

From Typescript 3.7 on, you can also use nullish coalescing:

let x = foo ?? bar();

Which is the equivalent for checking for null or undefined:

let x = (foo !== null && foo !== undefined) ?
    foo :

While not exactly the same, you could write your code as:

var uemail = localStorage.getItem("useremail") ?? alert('Undefined');

How to create a sticky footer that plays well with Bootstrap 3

What worked for me was adding the position relative to the html tag.

html {
body {
footer {

"FATAL: Module not found error" using modprobe

Ensure that your network is brought down before loading module:

sudo stop networking

It helped me -

How to increase request timeout in IIS?

I know the question was about ASP but maybe somebody will find this answer helpful.

If you have a server behind the IIS 7.5 (e.g. Tomcat). In my case I have a server farm with Tomcat server configured. In such case you can change the timeout using the IIS Manager:

  • go to Server Farms -> {Server Name} -> Proxy
  • change the value in the Time-out entry box
  • click Apply (top-right corner)

or you can change it in the cofig file:

  • open %WinDir%\System32\Inetsrv\Config\applicationHost.config
  • adjust the server webFarm configuration to be similar to the following


<webFarm name="${SERVER_NAME}" enabled="true"> 
  <server address="${SERVER_ADDRESS}" enabled="true">
    <applicationRequestRouting httpPort="${SERVER_PORT}" />
    <protocol timeout="${TIME}" />

The ${TIME} is in HH:mm:ss format (so if you want to set it to 90 seconds then put there 00:01:30)

In case of Tomcat (and probably other servlet containers) you have to remember to change the timeout in the %TOMCAT_DIR%\conf\server.xml (just search for connectionTimeout attribute in Connector tag, and remember that it is specified in milliseconds)

source command not found in sh shell

source is a bash built-in command so to execute source command, you can log in as Root.

sudo -s source ./

Padding In bootstrap

There are padding built into various classes.

For example:

A web forms app:

<asp:CheckBox ID="chkShowDeletedServers" runat="server" AutoPostBack="True" Text="Show Deleted" />

this code above would place the Text of "Show Deleted" too close to the checkbox to what I see at nice to look at.

However with bootstrap

<div class="checkbox-inline">
    <asp:CheckBox ID="chkShowDeletedServers" runat="server" AutoPostBack="True" Text="Show Deleted" />

This created the space, if you don't want the text bold, that class=checkbox

Bootstrap is very flexible, so in this case I don't need a hack, but sometimes you need to.

Error in setting JAVA_HOME

You are pointing your JAVA_HOME to the JRE which is the Java Runtime Environment. The runtime environment doesn't have a java compiler in its bin folder. You should download the JDK which is the Java Development Kit. Once you've installed that, you can see in your bin folder that there's a file called javac.exe. That's your compiler.

How to dynamically add and remove form fields in Angular 2

addAccordian(type, data) { console.log(type, data);

let form = this.form;

if (!form.controls[type]) {
  let ownerAccordian = new FormArray([]);
  const group = new FormGroup({});
    this.applicationService.createControlWithGroup(data, group)
  form.controls[type] = ownerAccordian;
} else {
  const group = new FormGroup({});
    this.applicationService.createControlWithGroup(data, group)


Bootstrap 3 only for mobile

I found a solution wich is to do:

<span class="visible-sm"> your code without col </span>
<span class="visible-xs"> your code with col </span>

It's not very optimized but it works. Did you find something better? It really miss a class like col-sm-0 to apply colons just to the xs size...

VB.NET Inputbox - How to identify when the Cancel Button is pressed?

Why not check if for nothing?

if not inputbox("bleh") = nothing then
' Error
end if

This is what i typically use, because its a little easier to read.

WordPress is giving me 404 page not found for all pages except the homepage

Just Navigate to Settings->Permalink in your dashboard and then Save Changes button in the last.\

Add image in title bar

you should be searching about how to add favicon.ico . You can try adding favicon.ico directly in your html pages like this

<link rel="shortcut icon" href="/favicon.png" type="image/png">
<link rel="shortcut icon" type="image/png" href="" />

Or you can update that in your webserver. It is advised to add in your webserver as you don't need to add this in each of your html pages (assuming no includes).

To add in your apache place the favicon.ico in your root website director and add this in httpd.conf

AddType image/x-icon .ico

Ruby on Rails: Where to define global constants?

Try to keep all constant at one place, In my application I have created constants folder inside initializers as follows:

enter image description here

and I usually keep all constant in these files.

In your case you can create file under constants folder as colors_constant.rb


enter image description here

Don't forgot to restart server

Convert JSON String to JSON Object c#

You can try like following:

string output = JsonConvert.SerializeObject(jsonStr);

Convert Rows to columns using 'Pivot' in SQL Server

Here is a revision of @Tayrn answer above that might help you understand pivoting a little easier:

This may not be the best way to do this, but this is what helped me wrap my head around how to pivot tables.

ID = rows you want to pivot

MY_KEY = the column you are selecting from your original table that contains the column names you want to pivot.

VAL = the value you want returning under each column.

MAX(VAL) => Can be replaced with other aggregiate functions. SUM(VAL), MIN(VAL), ETC...

select @cols = STUFF((SELECT ',' + QUOTENAME(MY_KEY) 
                from yt
                group by MY_KEY
                order by MY_KEY ASC
        FOR XML PATH(''), TYPE
        ).value('.', 'NVARCHAR(MAX)') 
set @query = 'SELECT ID,' + @cols + ' from 
            select ID, MY_KEY, VAL 
            from yt
        ) x
            for MY_KEY in (' + @cols + ')
        ) p '


An error occurred while executing the command definition. See the inner exception for details

Does the actual query return no results? First() will fail if there are no results.

How to cancel a local git commit

Use --soft instead of --hard flag:

git reset --soft HEAD^

How to write both h1 and h2 in the same line?

<h1 style="text-align: left; float: left;">Text 1</h1>
<h2 style="text-align: right; float: right; display: inline;">Text 2</h2>
<hr style="clear: both;" />

Hope this helps!

Git: Pull from other remote

git pull is really just a shorthand for git pull <remote> <branchname>, in most cases it's equivalent to git pull origin master. You will need to add another remote and pull explicitly from it. This page describes it in detail:

How to run script as another user without password?

`su -c "Your command right here" -s /bin/sh username`

The above command is correct, but on Red Hat if selinux is enforcing it will not allow cron to execute scripts as another user. example; execl: couldn't exec /bin/sh execl: Permission denied

I had to install setroubleshoot and setools and run the following to allow it:

yum install setroubleshoot setools
sealert -a /var/log/audit/audit.log
grep crond /var/log/audit/audit.log | audit2allow -M mypol
semodule -i mypol.p

How to maintain a Unique List in Java?

You may want to use one of the implementing class of java.util.Set<E> Interface e.g. java.util.HashSet<String> collection class.

A collection that contains no duplicate elements. More formally, sets contain no pair of elements e1 and e2 such that e1.equals(e2), and at most one null element. As implied by its name, this interface models the mathematical set abstraction.

PHP/MySQL: How to create a comment section in your website

I'm working on this right now as well. You should also add a datetime of the comment. You'll need this later when you want to sort by most recent.

Here are some of the db fields i'm using.

id (auto incremented)

CSS last-child(-1)

You can use :nth-last-child(); in fact, besides :nth-last-of-type() I don't know what else you could use. I'm not sure what you mean by "dynamic", but if you mean whether the style applies to the new second last child when more children are added to the list, yes it will. Interactive fiddle.

ul li:nth-last-child(2)

Java generics - get class?

I'm able to get the Class of the generic type this way:

class MyList<T> {
  Class<T> clazz = (Class<T>) DAOUtil.getTypeArguments(MyList.class, this.getClass()).get(0);

You need two functions from this file:

For more explanation:

What is the difference between compileSdkVersion and targetSdkVersion?

Late to the game.. and there are several great answers above-- essentially, that the compileSdkVersion is the version of the API the app is compiled against, while the targetSdkVersion indicates the version that the app was tested against.

I'd like to supplement those answers with the following notes:

  1. That targetSdkVersion impacts the way in which permissions are requested:
  • If the device is running Android 6.0 (API level 23) or higher, and the app's targetSdkVersion is 23 or higher, the app requests permissions from the user at run-time.
  • If the device is running Android 5.1 (API level 22) or lower, or the app's targetSdkVersion is 22 or lower, the system asks the user to grant the permissions when the user installs the app.
  1. If the compileSdkVersion is higher than the version declared by your app's targetSdkVersion, the system may enable compatibility behaviors to ensure that your app continues to work the way you expect. (ref)

  2. With each new Android release...

  • targetSdkVersion should be incremented to match the latest API level, then thoroughly test your application on the corresponding platform version
  • compileSdkVersion, on the other hand, does not need to be changed unless you're adding features exclusive to the new platform version
  • As a result, while targetSdkVersion is often (initially) less than than the compileSdkVersion, it's not uncommon to see a well-maintained/established app with targetSdkVersion > compileSdkVersion

How do I write data to csv file in columns and rows from a list in python?

Have a go with these code:

>>> import pyexcel as pe
>>> sheet = pe.Sheet(data)
>>> data=[[1, 2], [2, 3], [4, 5]]
>>> sheet
Sheet Name: pyexcel
| 1 | 2 |
| 2 | 3 |
| 4 | 5 |
>>> sheet.save_as("one.csv")
>>> b = [[126, 125, 123, 122, 123, 125, 128, 127, 128, 129, 130, 130, 128, 126, 124, 126, 126, 128, 129, 130, 130, 130, 130, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 132, 134, 134, 134, 134, 134, 134, 134, 134, 133, 134, 135, 134, 133, 133, 134, 135, 136], [135, 135, 136, 137, 137, 136, 134, 135, 135, 135, 134, 134, 133, 133, 133, 134, 134, 134, 133, 133, 132, 132, 132, 135, 135, 133, 133, 133, 133, 135, 135, 131, 135, 136, 134, 133, 136, 137, 136, 133, 134, 135, 136, 136, 135, 134, 133, 133, 134, 135, 136, 136, 136, 135, 134, 135, 138, 138, 135, 135, 138, 138, 135, 139], [137, 135, 136, 138, 139, 137, 135, 142, 139, 137, 139, 138, 136, 137, 141, 138, 138, 139, 139, 139, 139, 138, 138, 138, 138, 137, 137, 137, 137, 138, 138, 136, 137, 137, 137, 137, 137, 137, 138, 148, 144, 140, 138, 137, 138, 138, 138, 137, 137, 137, 137, 137, 138, 139, 140, 141, 141, 141, 141, 141, 141, 141, 141, 141], [141, 141, 141, 141, 141, 141, 141, 139, 139, 139, 140, 140, 141, 141, 141, 140, 140, 140, 140, 140, 141, 142, 143, 138, 138, 138, 139, 139, 140, 140, 140, 141, 140, 139, 139, 141, 141, 140, 139, 145, 137, 137, 145, 145, 137, 137, 144, 141, 139, 146, 134, 145, 140, 149, 144, 145, 142, 140, 141, 144, 145, 142, 139, 140]]
>>> s2 = pe.Sheet(b)
>>> s2
Sheet Name: pyexcel
| 126 | 125 | 123 | 122 | 123 | 125 | 128 | 127 | 128 | 129 | 130 | 130 | 128 | 126 | 124 | 126 | 126 | 128 | 129 | 130 | 130 | 130 | 130 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 132 | 134 | 134 | 134 | 134 | 134 | 134 | 134 | 134 | 133 | 134 | 135 | 134 | 133 | 133 | 134 | 135 | 136 |
| 135 | 135 | 136 | 137 | 137 | 136 | 134 | 135 | 135 | 135 | 134 | 134 | 133 | 133 | 133 | 134 | 134 | 134 | 133 | 133 | 132 | 132 | 132 | 135 | 135 | 133 | 133 | 133 | 133 | 135 | 135 | 131 | 135 | 136 | 134 | 133 | 136 | 137 | 136 | 133 | 134 | 135 | 136 | 136 | 135 | 134 | 133 | 133 | 134 | 135 | 136 | 136 | 136 | 135 | 134 | 135 | 138 | 138 | 135 | 135 | 138 | 138 | 135 | 139 |
| 137 | 135 | 136 | 138 | 139 | 137 | 135 | 142 | 139 | 137 | 139 | 138 | 136 | 137 | 141 | 138 | 138 | 139 | 139 | 139 | 139 | 138 | 138 | 138 | 138 | 137 | 137 | 137 | 137 | 138 | 138 | 136 | 137 | 137 | 137 | 137 | 137 | 137 | 138 | 148 | 144 | 140 | 138 | 137 | 138 | 138 | 138 | 137 | 137 | 137 | 137 | 137 | 138 | 139 | 140 | 141 | 141 | 141 | 141 | 141 | 141 | 141 | 141 | 141 |
| 141 | 141 | 141 | 141 | 141 | 141 | 141 | 139 | 139 | 139 | 140 | 140 | 141 | 141 | 141 | 140 | 140 | 140 | 140 | 140 | 141 | 142 | 143 | 138 | 138 | 138 | 139 | 139 | 140 | 140 | 140 | 141 | 140 | 139 | 139 | 141 | 141 | 140 | 139 | 145 | 137 | 137 | 145 | 145 | 137 | 137 | 144 | 141 | 139 | 146 | 134 | 145 | 140 | 149 | 144 | 145 | 142 | 140 | 141 | 144 | 145 | 142 | 139 | 140 |
>>> s2[0,0]
>>> s2.save_as("two.csv")

What does EntityManager.flush do and why do I need to use it?

The EntityManager.flush() operation can be used the write all changes to the database before the transaction is committed. By default JPA does not normally write changes to the database until the transaction is committed. This is normally desirable as it avoids database access, resources and locks until required. It also allows database writes to be ordered, and batched for optimal database access, and to maintain integrity constraints and avoid deadlocks. This means that when you call persist, merge, or remove the database DML INSERT, UPDATE, DELETE is not executed, until commit, or until a flush is triggered.

Get local href value from anchor (a) tag

This code works for me to get all links of the document

var links=document.getElementsByTagName('a'), hrefs = [];
for (var i = 0; i<links.length; i++)

ReportViewer Client Print Control "Unable to load client print control"?

I got this working with out removing any patches. The above patch was not working too. Finally what I did was on the IIS server install the following patch and reset / restart the IIS server. This is not for report manager application. This is for any ASP.NET Web application developed in .net3.5 using VS2008

Drop default constraint on a column in TSQL

This is how you would drop the constraint

ALTER TABLE <schema_name, sysname, dbo>.<table_name, sysname, table_name>
   DROP CONSTRAINT <default_constraint_name, sysname, default_constraint_name>

With a script

-- t-sql scriptlet to drop all constraints on a table
DECLARE @database nvarchar(50)
DECLARE @table nvarchar(50)

set @database = 'dotnetnuke'
set @table = 'tabs'

DECLARE @sql nvarchar(255)
WHILE EXISTS(select * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS where constraint_catalog = @database and table_name = @table)
    select    @sql = 'ALTER TABLE ' + @table + ' DROP CONSTRAINT ' + CONSTRAINT_NAME 
    where    constraint_catalog = @database and 
            table_name = @table
    exec    sp_executesql @sql

Credits go to Jon Galloway

How to print all session variables currently set?

this worked for me:-

<?php echo '<pre>' . print_r($_SESSION, TRUE) . '</pre>'; ?>

thanks for sharing code...

    [__ci_last_regenerate] => 1490879962

    [user_id] => 3

    [designation_name] => Admin
    [region_name] => admin
    [territory_name] => admin
    [designation_id] => 2
    [region_id] => 1
    [territory_id] => 1
    [employee_user_id] => mosin11

IllegalArgumentException or NullPointerException for a null parameter?

In general, a developer should never throw a NullPointerException. This exception is thrown by the runtime when code attempts to dereference a variable who's value is null. Therefore, if your method wants to explicitly disallow null, as opposed to just happening to have a null value raise a NullPointerException, you should throw an IllegalArgumentException.

Convert unsigned int to signed int C

I know it's an old question, but it's a good one, so how about this?

unsigned short int x = 65529U;
short int y = *(short int*)&x;

printf("%d\n", y);

Trim string in JavaScript?

If you are using jQuery, use the jQuery.trim() function. For example:

if( jQuery.trim(StringVariable) == '')

Finding the index of elements based on a condition using python list comprehension

For me it works well:

>>> import numpy as np
>>> a = np.array([1, 2, 3, 1, 2, 3])
>>> np.where(a > 2)[0]
[2 5]

How to use sudo inside a docker container?

Unlike accepted answer, I use usermod instead.

Assume already logged-in as root in docker, and "fruit" is the new non-root username I want to add, simply run this commands:

apt update && apt install sudo
adduser fruit
usermod -aG sudo fruit

Remember to save image after update. Use docker ps to get current running docker's <CONTAINER ID> and <IMAGE>, then run docker commit -m "added sudo user" <CONTAINER ID> <IMAGE> to save docker image.

Then test with:

su fruit
sudo whoami

Or test by direct login(ensure save image first) as that non-root user when launch docker:

docker run -it --user fruit <IMAGE>
sudo whoami

You can use sudo -k to reset password prompt timestamp:

sudo whoami # No password prompt
sudo -k # Invalidates the user's cached credentials
sudo whoami # This will prompt for password

How to return multiple rows from the stored procedure? (Oracle PL/SQL)

create procedure <procedure_name>(p_cur out sys_refcursor) as begin open p_cur for select * from <table_name> end;

How can I add a key/value pair to a JavaScript object?

We can add a key/value pair to a JavaScript object in many ways...

CASE - 1 : Expanding an object
Using this we can add multiple key: value to the object at the same time.

const rectangle = { width: 4, height: 6 };
const cube = {...rectangle, length: 7};
const cube2 = {...rectangle, length: 7, stroke: 2};
  console.log("Cube2: ", cube2);
  console.log("Cube: ", cube);
  console.log("Rectangle: ", rectangle);

CASE - 2 : Using dot notation

var rectangle = { width: 4, height: 6 };
rectangle.length = 7;

CASE - 3 : Using [square] notation

var rectangle = { width: 4, height: 6 };
    rectangle["length"] = 7;

Razor If/Else conditional operator syntax

You need to put the entire ternary expression in parenthesis. Unfortunately that means you can't use "@:", but you could do something like this:

@(deletedView ? "Deleted" : "Created by")

Razor currently supports a subset of C# expressions without using @() and unfortunately, ternary operators are not part of that set.

Alter a SQL server function to accept new optional parameter


When a parameter of the function has a default value, the keyword DEFAULT must be specified when the function is called to retrieve the default value. This behavior is different from using parameters with default values in stored procedures in which omitting the parameter also implies the default value.

So you need to do:

SELECT dbo.fCalculateEstimateDate(647,DEFAULT)

Principal Component Analysis (PCA) in Python

This is a job for numpy.

And here's a tutorial demonstrating how pincipal component analysis can be done using numpy's built-in modules like mean,cov,double,cumsum,dot,linalg,array,rank.

Notice that scipy also has a long explanation here -

with the scikit-learn library having more code examples -

How to split the screen with two equal LinearLayouts?

Just putting it out there:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
    android:padding="5dp"> <!-- to show what the parent is -->
        android:layout_weight="2" />
        android:layout_weight="1" />

How does the getView() method work when creating your own custom adapter?

LayoutInflater is used to generate dynamic views of the XML for the ListView item or in onCreateView of the fragment.

ConvertView is basically used to recycle the views which are not in the view currently. Say you have a scrollable ListView. On scrolling down or up, the convertView gives the view which was scrolled. This reusage saves memory.

The parent parameter of the getView() method gives a reference to the parent layout which has the listView. Say you want to get the Id of any item in the parent XML you can use:

ViewParent nv = parent.getParent();

while (nv != null) {

    if (View.class.isInstance(nv)) {
        final View button = ((View) nv).findViewById(;
        if (button != null) {
            // FOUND IT!
            // do something, then break;
            button.setOnClickListener(new OnClickListener() {

                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    Log.d("Remove", "Remove clicked");

                    ((Button) button).setText("Hi");


How to get share counts using graph API

What I found useful and I found on one link above is this FQL query where you ask for likes, total, share and click count of one link by looking at the link_stat table,%20total_count,%20share_count,%20click_count,%20comment_count%20FROM%20link_stat%20WHERE%20url%20=%20%22

That will output something like this:

    data: [
             like_count: 3440162,
             total_count: 13226503,
             share_count: 7732740,
             click_count: 265614,
             comment_count: 2053601

What is the alternative for ~ (user's home directory) on Windows command prompt?

You can do almost the same yourself. Open Environment Variables and click "New" Button in the "User Variables for ..." .
Variable Name: ~
Variable Value: Click "Browse Directory..." button and choose a directory which you want.

And after this, open cmd and type this:
cd %~%
. It works.

Maximum call stack size exceeded on npm install

npm cache clean returns below message

As of npm@5, the npm cache self-heals from corruption issues and data extracted from the cache is guaranteed to be valid. If you want to make sure everything is consistent, use 'npm cache verify' instead. On the other hand, if you're debugging an issue with the installer, you can use npm install --cache /tmp/empty-cache to use a temporary cache instead of nuking the actual one.

If you run npm cache verify, as specified above, then it actually runs cache verification and garbage collection which fixes the problem.

Cache verified and compressed (~\AppData\Roaming\npm-cache_cacache): Content verified: 6183 (447214684 bytes) Content garbage-collected: 16 (653745 bytes) Index entries: 9633

Disabling swap files creation in vim

create no vim swap file just for a particular file

autocmd bufenter  c:/aaa/Dropbox/TapNote/Todo.txt :set noswapfile

How to obtain the start time and end time of a day?

in getEndOfDay, you can add:

calendar.set(Calendar.MILLISECOND, 999);

Although mathematically speaking, you can't specify the end of a day other than by saying it's "before the beginning of the next day".

So instead of saying, if(date >= getStartOfDay(today) && date <= getEndOfDay(today)), you should say: if(date >= getStartOfDay(today) && date < getStartOfDay(tomorrow)). That is a much more solid definition (and you don't have to worry about millisecond precision).

YAML: Do I need quotes for strings in YAML?

After a brief review of the YAML cookbook cited in the question and some testing, here's my interpretation:

  • In general, you don't need quotes.
  • Use quotes to force a string, e.g. if your key or value is 10 but you want it to return a String and not a Fixnum, write '10' or "10".
  • Use quotes if your value includes special characters, (e.g. :, {, }, [, ], ,, &, *, #, ?, |, -, <, >, =, !, %, @, \).
  • Single quotes let you put almost any character in your string, and won't try to parse escape codes. '\n' would be returned as the string \n.
  • Double quotes parse escape codes. "\n" would be returned as a line feed character.
  • The exclamation mark introduces a method, e.g. !ruby/sym to return a Ruby symbol.

Seems to me that the best approach would be to not use quotes unless you have to, and then to use single quotes unless you specifically want to process escape codes.


"Yes" and "No" should be enclosed in quotes (single or double) or else they will be interpreted as TrueClass and FalseClass values:

    'yes': 'Yes'
    'no': 'No'

Mapping a JDBC ResultSet to an object

I would like to hint on q2o. It is a JPA based Java object mapper which helps with many of the tedious SQL and JDBC ResultSet related tasks, but without all the complexity an ORM framework comes with. With its help mapping a ResultSet to an object is as easy as this:

while( {
    users.add(Q2Obj.fromResultSet(rs, User.class));

More about q2o can be found here.

Get querystring from URL using jQuery

Have a look at this Stack Overflow answer.

 function getParameterByName(name, url) {
     if (!url) url = window.location.href;
     name = name.replace(/[\[\]]/g, "\\$&");
     var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
         results = regex.exec(url);
     if (!results) return null;
     if (!results[2]) return '';
     return decodeURIComponent(results[2].replace(/\+/g, " "));

You can use the method to animate:


var thequerystring = getParameterByName("location");
$('html,body').animate({scrollTop: $("div#" + thequerystring).offset().top}, 500);

How to catch a click event on a button?

Change your onCreate to

protected void onCreate(Bundle savedInstanceState) {

for me this update worked

Get second child using jQuery

It's surprising to see that nobody mentioned the native JS way to do this..

Without jQuery:

Just access the children property of the parent element. It will return a live HTMLCollection of children elements which can be accessed by an index. If you want to get the second child:


In your case, something like this could work: (example)

var secondChild = document.querySelector('.parent').children[1];

console.log(secondChild); // <td>element two</td>
    <tr class="parent">
        <td>element one</td>
        <td>element two</td>

You can also use a combination of CSS3 selectors / querySelector() and utilize :nth-of-type(). This method may work better in some cases, because you can also specifiy the element type, in this case td:nth-of-type(2) (example)

var secondChild = document.querySelector('.parent > td:nth-of-type(2)');

console.log(secondChild); // <td>element two</td>

How to disable sort in DataGridView?

If you can extend the DataGridView you can override the Sort method with am empty one. This disables Sort for the DataGridView entirely.

public override void Sort(DataGridViewColumn dataGridViewColumn, ListSortDirection direction)
    //base.Sort(dataGridViewColumn, direction);

Note: You cannot even programmatically sort any column.

Efficient way to update all rows in a table

Might not work you for, but a technique I've used a couple times in the past for similar circumstances.

created updated_{table_name}, then select insert into this table in batches. Once finished, and this hinges on Oracle ( which I don't know or use ) supporting the ability to rename tables in an atomic fashion. updated_{table_name} becomes {table_name} while {table_name} becomes original_{table_name}.

Last time I had to do this was for a heavily indexed table with several million rows that absolutely positively could not be locked for the duration needed to make some serious changes to it.

Setting the selected attribute on a select list using jQuery

$('#select_id option:eq(0)').prop('selected', 'selected');

its good

How to list all Git tags?

To list tags I prefer:

git tag -n

The -n flag displays the first line of the annotation message along with the tag, or the first commit message line if the tag is not annotated.

You can also do git tag -n5 to show the first 5 lines of the annotation.

Create a hexadecimal colour based on a string with JavaScript

I find that generating random colors tends to create colors that do not have enough contrast for my taste. The easiest way I have found to get around that is to pre-populate a list of very different colors. For every new string, assign the next color in the list:

// Takes any string and converts it into a #RRGGBB color.
var StringToColor = (function(){
    var instance = null;

    return {
    next: function stringToColor(str) {
        if(instance === null) {
            instance = {};
            instance.stringToColorHash = {};
            instance.nextVeryDifferntColorIdx = 0;
            instance.veryDifferentColors = ["#000000","#00FF00","#0000FF","#FF0000","#01FFFE","#FFA6FE","#FFDB66","#006401","#010067","#95003A","#007DB5","#FF00F6","#FFEEE8","#774D00","#90FB92","#0076FF","#D5FF00","#FF937E","#6A826C","#FF029D","#FE8900","#7A4782","#7E2DD2","#85A900","#FF0056","#A42400","#00AE7E","#683D3B","#BDC6FF","#263400","#BDD393","#00B917","#9E008E","#001544","#C28C9F","#FF74A3","#01D0FF","#004754","#E56FFE","#788231","#0E4CA1","#91D0CB","#BE9970","#968AE8","#BB8800","#43002C","#DEFF74","#00FFC6","#FFE502","#620E00","#008F9C","#98FF52","#7544B1","#B500FF","#00FF78","#FF6E41","#005F39","#6B6882","#5FAD4E","#A75740","#A5FFD2","#FFB167","#009BFF","#E85EBE"];

            instance.stringToColorHash[str] = instance.veryDifferentColors[instance.nextVeryDifferntColorIdx++];

            return instance.stringToColorHash[str];

// Get a new color for each string"get first color");"get second color");

// Will return the same color as the first time"get first color");

While this has a limit to only 64 colors, I find most humans can't really tell the difference after that anyway. I suppose you could always add more colors.

While this code uses hard-coded colors, you are at least guaranteed to know during development exactly how much contrast you will see between colors in production.

Color list has been lifted from this SO answer, there are other lists with more colors.

Pandas : compute mean or std (standard deviation) over entire dataframe

You could convert the dataframe to be a single column with stack (this changes the shape from 5x3 to 15x1) and then take the standard deviation:

df.stack().std()         # pandas default degrees of freedom is one

Alternatively, you can use values to convert from a pandas dataframe to a numpy array before taking the standard deviation:

df.values.std(ddof=1)    # numpy default degrees of freedom is zero

Unlike pandas, numpy will give the standard deviation of the entire array by default, so there is no need to reshape before taking the standard deviation.

A couple of additional notes:

  • The numpy approach here is a bit faster than the pandas one, which is generally true when you have the option to accomplish the same thing with either numpy or pandas. The speed difference will depend on the size of your data, but numpy was roughly 10x faster when I tested a few different sized dataframes on my laptop (numpy version 1.15.4 and pandas version 0.23.4).

  • The numpy and pandas approaches here will not give exactly the same answers, but will be extremely close (identical at several digits of precision). The discrepancy is due to slight differences in implementation behind the scenes that affect how the floating point values get rounded.

Class name does not name a type in C++

You must first include B.h from A.h. B b; makes no sense until you have included B.h.

Extract substring using regexp in plain bash

Using pure :

$ cat file.txt
US/Central - 10:26 PM (CST)
$ while read a b time x; do [[ $b == - ]] && echo $time; done < file.txt

another solution with bash regex :

$ [[ "US/Central - 10:26 PM (CST)" =~ -[[:space:]]*([0-9]{2}:[0-9]{2}) ]] &&
    echo ${BASH_REMATCH[1]}

another solution using grep and look-around advanced regex :

$ echo "US/Central - 10:26 PM (CST)" | grep -oP "\-\s+\K\d{2}:\d{2}"

another solution using sed :

$ echo "US/Central - 10:26 PM (CST)" |
    sed 's/.*\- *\([0-9]\{2\}:[0-9]\{2\}\).*/\1/'

another solution using perl :

$ echo "US/Central - 10:26 PM (CST)" |
    perl -lne 'print $& if /\-\s+\K\d{2}:\d{2}/'

and last one using awk :

$ echo "US/Central - 10:26 PM (CST)" |
    awk '{for (i=0; i<=NF; i++){if ($i == "-"){print $(i+1);exit}}}'

How to change maven logging level to display only warning and errors?

The simplest way is to upgrade to Maven 3.3.1 or higher to take advantage of the ${maven.projectBasedir}/.mvn/jvm.config support.

Then you can use any options from Maven's SL4FJ's SimpleLogger support to configure all loggers or particular loggers. For example, here is a how to make all warning at warn level, except for a the PMD which is configured to log at error:

cat .mvn/jvm.config

See here for more details on logging with Maven.

Installing Bower on Ubuntu

At Least from Ubuntu 12.04, an old version (0.6.x) of Node is in the standard repository. To install, just run:

sudo apt-get install nodejs

NPM comes with latest version of nodejs. Once you have that, then run

sudo npm install bower -g

Should be good to go after that. You may need to run some updates, but it should be fairly straight forward.