Programs & Examples On #Thinking sphinx

Thinking Sphinx is a Ruby library that connects ActiveRecord models to the Sphinx search service.

How can I change the size of a Bootstrap checkbox?

It is possible in css, but not for all the browsers.

The effect on all browsers:

A possibility is a custom checkbox with javascript:

Get selected row item in DataGrid WPF

@Krytox answer with MVVM

        Margin="10" Grid.RowSpan="2"
        ItemsSource="{Binding Data_Table}"
        SelectedItem="{Binding Select_Request, Mode=TwoWay}" SelectionChanged="DataGrid_SelectionChanged"/>//The binding

    #region View Model
    private DataRowView select_request;
    public DataRowView Select_Request
        get { return select_request; }
            select_request = value;
            OnPropertyChanged("Select_Request"); //INotifyPropertyChange
            OnSelect_RequestChange();//do stuff

Difference between break and continue statement

Simple Example:

break leaves the loop.

int m = 0;
for(int n = 0; n < 5; ++n){
  if(n == 2){

System.out.printl("m:"+m); // m:2

continue will go back to start loop.

int m = 0;
for(int n = 0; n < 5; ++n){
  if(n == 2){
    continue; // Go back to start and dont execute m++

System.out.printl("m:"+m); // m:4

Java verify void method calls n times with Mockito

The necessary method is Mockito#verify:

public static <T> T verify(T mock,
                           VerificationMode mode)

mock is your mocked object and mode is the VerificationMode that describes how the mock should be verified. Possible modes are:

verify(mock, times(5)).someMethod("was called five times");
verify(mock, never()).someMethod("was never called");
verify(mock, atLeastOnce()).someMethod("was called at least once");
verify(mock, atLeast(2)).someMethod("was called at least twice");
verify(mock, atMost(3)).someMethod("was called at most 3 times");
verify(mock, atLeast(0)).someMethod("was called any number of times"); // useful with captors
verify(mock, only()).someMethod("no other method has been called on the mock");

You'll need these static imports from the Mockito class in order to use the verify method and these verification modes:

import static org.mockito.Mockito.atLeast;
import static org.mockito.Mockito.atLeastOnce;
import static org.mockito.Mockito.atMost;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.only;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;

So in your case the correct syntax will be:

Mockito.verify(mock, times(4)).send()

This verifies that the method send was called 4 times on the mocked object. It will fail if it was called less or more than 4 times.

If you just want to check, if the method has been called once, then you don't need to pass a VerificationMode. A simple

verify(mock).someMethod("was called once");

would be enough. It internally uses verify(mock, times(1)).someMethod("was called once");.

It is possible to have multiple verification calls on the same mock to achieve a "between" verification. Mockito doesn't support something like this verify(mock, between(4,6)).someMethod("was called between 4 and 6 times");, but we can write

verify(mock, atLeast(4)).someMethod("was called at least four times ...");
verify(mock, atMost(6)).someMethod("... and not more than six times");

instead, to get the same behaviour. The bounds are included, so the test case is green when the method was called 4, 5 or 6 times.

Is it possible to get element from HashMap by its position?

Use LinkedHashMap and use this function.

private LinkedHashMap<Integer, String> map = new LinkedHashMap<Integer, String>();

Define like this and.

private Entry getEntry(int id){
        Iterator iterator = map.entrySet().iterator();
        int n = 0;
            Entry entry = (Entry);
            if(n == id){
                return entry;
            n ++;
        return null;

The function can return the selected entry.

Pods stuck in Terminating status

please try below command : kubectl patch pod -p '{"metadata":{"finalizers":null}}'

How to send redirect to JSP page in Servlet

Look at the HttpServletResponse#sendRedirect(String location) method.

Use it as:

response.sendRedirect(request.getContextPath() + "/welcome.jsp")

Alternatively, look at HttpServletResponse#setHeader(String name, String value) method.

The redirection is set by adding the location header:

response.setHeader("Location", request.getContextPath() + "/welcome.jsp");

Using Mockito with multiple calls to the same method with the same arguments

Following can be used as a common method to return different arguments on different method calls. Only thing we need to do is we need to pass an array with order in which objects should be retrieved in each call.

public static <Mock> Answer<Mock> getAnswerForSubsequentCalls(final Mock... mockArr) {
    return new Answer<Mock>() {
       private int count=0, size=mockArr.length;
       public Mock answer(InvocationOnMock invocation) throws throwable {
           Mock mock = null;
           for(; count<size && mock==null; count++){
                mock = mockArr[count];

           return mock;    

Ex. getAnswerForSubsequentCalls(mock1, mock3, mock2); will return mock1 object on first call, mock3 object on second call and mock2 object on third call. Should be used like when(something()).doAnswer(getAnswerForSubsequentCalls(mock1, mock3, mock2)); This is almost similar to when(something()).thenReturn(mock1, mock3, mock2);

jQuery - Fancybox: But I don't want scrollbars!

My 2 cents, write

*{ margin:0; padding:0; }

in your target page main css, add a content div with the height size of all your elements, don't touch the .js, listo, saludos

Getting attributes of Enum's value

This is a generic implementation using a lambda for the selection

public static Expected GetAttributeValue<T, Expected>(this Enum enumeration, Func<T, Expected> expression)
    where T : Attribute
    T attribute =
        .Where(member => member.MemberType == MemberTypes.Field)
        .GetCustomAttributes(typeof(T), false)

    if (attribute == null)
        return default(Expected);

    return expression(attribute);

Call it like this:

string description = targetLevel.GetAttributeValue<DescriptionAttribute, string>(x => x.Description);

Multipart forms from C# client

A little optimization of the class before. In this version the files are not totally loaded into memory.

Security advice: a check for the boundary is missing, if the file contains the bounday it will crash.

namespace WindowsFormsApplication1
    public static class FormUpload
        private static string NewDataBoundary()
            Random rnd = new Random();
            string formDataBoundary = "";
            while (formDataBoundary.Length < 15)
                formDataBoundary = formDataBoundary + rnd.Next();
            formDataBoundary = formDataBoundary.Substring(0, 15);
            formDataBoundary = "-----------------------------" + formDataBoundary;
            return formDataBoundary;

        public static HttpWebResponse MultipartFormDataPost(string postUrl, IEnumerable<Cookie> cookies, Dictionary<string, string> postParameters)
            string boundary = NewDataBoundary();

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(postUrl);

            // Set up the request properties
            request.Method = "POST";
            request.ContentType = "multipart/form-data; boundary=" + boundary;
            request.UserAgent = "PhasDocAgent 1.0";
            request.CookieContainer = new CookieContainer();

            foreach (var cookie in cookies)

            #region WRITING STREAM
            using (Stream formDataStream = request.GetRequestStream())
                foreach (var param in postParameters)
                    if (param.Value.StartsWith("file://"))
                        string filepath = param.Value.Substring(7);

                        // Add just the first part of this param, since we will write the file data directly to the Stream
                        string header = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"; filename=\"{2}\";\r\nContent-Type: {3}\r\n\r\n",
                            Path.GetFileName(filepath) ?? param.Key,

                        formDataStream.Write(Encoding.UTF8.GetBytes(header), 0, header.Length);

                        // Write the file data directly to the Stream, rather than serializing it to a string.

                        byte[] buffer = new byte[2048];

                        FileStream fs = new FileStream(filepath, FileMode.Open);

                        for (int i = 0; i < fs.Length; )
                            int k = fs.Read(buffer, 0, buffer.Length);
                            if (k > 0)
                                formDataStream.Write(buffer, 0, k);
                            i = i + k;
                        string postData = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"\r\n\r\n{2}\r\n",
                        formDataStream.Write(Encoding.UTF8.GetBytes(postData), 0, postData.Length);
                // Add the end of the request
                byte[] footer = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");
                formDataStream.Write(footer, 0, footer.Length);
                request.ContentLength = formDataStream.Length;

            return request.GetResponse() as HttpWebResponse;

How to iterate through SparseArray?

The accepted answer has some holes in it. The beauty of the SparseArray is that it allows gaps in the indeces. So, we could have two maps like so, in a SparseArray...


Notice the size here would be 2. If we iterate over size, we will only get values for the values mapped to index 0 and index 1. So the mapping with a key of 250 is not accessed.

for(int i = 0; i < sparseArray.size(); i++) {
   int key = sparseArray.keyAt(i);
   // get the object by the key.
   Object obj = sparseArray.get(key);

The best way to do this is to iterate over the size of your data set, then check those indeces with a get() on the array. Here is an example with an adapter where I am allowing batch delete of items.

for (int index = 0; index < mAdapter.getItemCount(); index++) {
     if (toDelete.get(index) == true) {
        long idOfItemToDelete = (allItems.get(index).getId());

I think ideally the SparseArray family would have a getKeys() method, but alas it does not.

PostgreSQL : cast string to date DD/MM/YYYY

A DATE column does not have a format. You cannot specify a format for it.

You can use DateStyle to control how PostgreSQL emits dates, but it's global and a bit limited.

Instead, you should use to_char to format the date when you query it, or format it in the client application. Like:

SELECT to_char("date", 'DD/MM/YYYY') FROM mytable;


regress=> SELECT to_char(DATE '2014-04-01', 'DD/MM/YYYY');
(1 row)

Read a zipped file as a pandas DataFrame

If you want to read a zipped or a tar.gz file into pandas dataframe, the read_csv methods includes this particular implementation.

df = pd.read_csv('')

Or the long form:

df = pd.read_csv('', compression='zip', header=0, sep=',', quotechar='"')

Description of the compression argument from the docs:

compression : {‘infer’, ‘gzip’, ‘bz2’, ‘zip’, ‘xz’, None}, default ‘infer’ For on-the-fly decompression of on-disk data. If ‘infer’ and filepath_or_buffer is path-like, then detect compression from the following extensions: ‘.gz’, ‘.bz2’, ‘.zip’, or ‘.xz’ (otherwise no decompression). If using ‘zip’, the ZIP file must contain only one data file to be read in. Set to None for no decompression.

New in version 0.18.1: support for ‘zip’ and ‘xz’ compression.

How to replace a string in multiple files in linux command line

If the file contains backslashes (paths usually) you can try something like this:

sed -i -- 's,<path1>,<path2>,g' *


sed -i -- 's,/foo/bar,/new/foo/bar,g' *.sh (in all shell scripts available)

Where can I download Spring Framework jars without using Maven?

Please edit to keep this list of mirrors current

I found this maven repo where you could download from directly a zip file containing all the jars you need.

Alternate solution: Maven

The solution I prefer is using Maven, it is easy and you don't have to download each jar alone. You can do it with the following steps:

  1. Create an empty folder anywhere with any name you prefer, for example spring-source

  2. Create a new file named pom.xml

  3. Copy the xml below into this file

  4. Open the spring-source folder in your console

  5. Run mvn install

  6. After download finished, you'll find spring jars in /spring-source/target/dependencies

    <project xmlns="" xmlns:xsi="" xsi:schemaLocation="">

Also, if you need to download any other spring project, just copy the dependency configuration from its corresponding web page.

For example, if you want to download Spring Web Flow jars, go to its web page, and add its dependency configuration to the pom.xml dependencies, then run mvn install again.


binning data in python with scipy/numpy

The Scipy (>=0.11) function scipy.stats.binned_statistic specifically addresses the above question.

For the same example as in the previous answers, the Scipy solution would be

import numpy as np
from scipy.stats import binned_statistic

data = np.random.rand(100)
bin_means = binned_statistic(data, data, bins=10, range=(0, 1))[0]

Unable to verify leaf signature

I had the same issues. I have followed @ThomasReggi and @CoolAJ86 solution and worked well but I'm not satisfied with the solution.

Because "UNABLE_TO_VERIFY_LEAF_SIGNATURE" issue is happened due to certification configuration level.

I accept @thirdender solution but its partial solution.As per the nginx official website, they clearly mentioned certificate should be combination of The server certificate and chained certificates.

enter image description here

How to resolve symbolic links in a shell script

Here I present what I believe to be a cross-platform (Linux and macOS at least) solution to the answer that is working well for me currently.

    local ref="$1"
    if [ -x "$(which realpath)" ]; then
        path="$(realpath "$ref")"
        path="$(readlink -f "$ref" 2> /dev/null)"
        if [ $? -gt 0 ]; then
            if [ -x "$(which readlink)" ]; then
                if [ ! -z "$(readlink "$ref")" ]; then
                    ref="$(readlink "$ref")"
                echo "realpath and readlink not available. The following may not be the final path." 1>&2
            if [ -d "$ref" ]; then
                path="$(cd "$ref"; pwd -P)"
                path="$(cd $(dirname "$ref"); pwd -P)/$(basename "$ref")"
    echo "$path"

Here is a macOS (only?) solution. Possibly better suited to the original question.

    local ref="$1"
    if [[ ! -z "$(readlink "$ref")" ]]; then
        ref="$(readlink "$1")"
    if [[ -d "$ref" ]]; then
        echo "$(cd "$ref"; pwd -P)"
        echo "$(cd $(dirname "$ref"); pwd -P)/$(basename "$ref")"

AngularJS - Value attribute on an input text box is ignored when there is a ng-model used?

Overriding the input directive does seem to do the job. I made some minor alterations to Dan Hunsaker's code:

  • Added a check for ngModel before trying to use $parse().assign() on fields without a ngModel attributes.
  • Corrected the assign() function param order.
app.directive('input', function ($parse) {
  return {
    restrict: 'E',
    require: '?ngModel',
    link: function (scope, element, attrs) {
      if (attrs.ngModel && attrs.value) {
        $parse(attrs.ngModel).assign(scope, attrs.value);

jquery, domain, get URL

If you need from string, like me, use this function - it really works.

function getHost(url)
    var a = document.createElement('a');
    a.href = url;
    return a.hostname;

But note, if there is a subdomain (e.g. www.) in the URL it will get returned with the hostname. Conversely, if there is no subdomain the hostname will not have one either.

Replace a newline in TSQL

In SQL Server 2017 & later, use Trim

Select Trim(char(10) + char(13) from @str)
  1. it trims on starting and ending, not in the middle
  2. the order of \r and \n does not matter

I use it to trim special characters for a file name

Select Trim(char(10) + char(13) + ' *<>' from @fileName)

How to post an array of complex objects with JSON, jQuery to ASP.NET MVC Controller?

I've found an solution. I use an solution of Steve Gentile, jQuery and ASP.NET MVC – sending JSON to an Action – Revisited.

My ASP.NET MVC view code looks like:

function getplaceholders() {
        var placeholders = $('.ui-sortable');
        var results = new Array();
        placeholders.each(function() {
            var ph = $(this).attr('id');
            var sections = $(this).find('.sort');
            var section;

            sections.each(function(i, item) {
                var sid = $(item).attr('id');
                var o = { 'SectionId': sid, 'Placeholder': ph, 'Position': i };
        var postData = { widgets: results };
        var widgets = results;
            url: '/portal/Designer.mvc/SaveOrUpdate',
            type: 'POST',
            dataType: 'json',
            data: $.toJSON(widgets),
            contentType: 'application/json; charset=utf-8',
            success: function(result) {

and my controller action is decorated with an custom attribute

[JsonFilter(Param = "widgets", JsonDataType = typeof(List<PageDesignWidget>))]
public JsonResult SaveOrUpdate(List<PageDesignWidget> widgets

Code for the custom attribute can be found here (the link is broken now).

Because the link is broken this is the code for the JsonFilterAttribute

public class JsonFilter : ActionFilterAttribute
    public string Param { get; set; }
    public Type JsonDataType { get; set; }
    public override void OnActionExecuting(ActionExecutingContext filterContext)
        if (filterContext.HttpContext.Request.ContentType.Contains("application/json"))
            string inputContent;
            using (var sr = new StreamReader(filterContext.HttpContext.Request.InputStream))
                inputContent = sr.ReadToEnd();
            var result = JsonConvert.DeserializeObject(inputContent, JsonDataType);
            filterContext.ActionParameters[Param] = result;

JsonConvert.DeserializeObject is from Json.NET

Link: Serializing and Deserializing JSON with Json.NET

How to center an iframe horizontally?

You can put iframe inside a <div>


It works because it is now inside a block element.

How can I exclude one word with grep?

I've a directory with a bunch of files. I want to find all the files that DO NOT contain the string "speedup" so I successfully used the following command:

grep -iL speedup *

Why is char[] preferred over String for passwords?

Some people believe that you have to overwrite the memory used to store the password once you no longer need it. This reduces the time window an attacker has to read the password from your system and completely ignores the fact that the attacker already needs enough access to hijack the JVM memory to do this. An attacker with that much access can catch your key events making this completely useless (AFAIK, so please correct me if I am wrong).


Thanks to the comments I have to update my answer. Apparently there are two cases where this can add a (very) minor security improvement as it reduces the time a password could land on the hard drive. Still I think it's overkill for most use cases.

  • Your target system may be badly configured or you have to assume it is and you have to be paranoid about core dumps (can be valid if the systems are not managed by an administrator).
  • Your software has to be overly paranoid to prevent data leaks with the attacker gaining access to the hardware - using things like TrueCrypt (discontinued), VeraCrypt, or CipherShed.

If possible, disabling core dumps and the swap file would take care of both problems. However, they would require administrator rights and may reduce functionality (less memory to use) and pulling RAM from a running system would still be a valid concern.

Trying to get property of non-object - Laravel 5

If you working with or loops (for, foreach, etc.) or relationships (one to many, many to many, etc.), this may mean that one of the queries is returning a null variable or a null relationship member.

For example: In a table, you may want to list users with their roles.

    @foreach ($users as $user)
        <td>{{ $user->name }}</td>
        <td>{{ $user->role->name }}</td>

In the above case, you may receive this error if there is even one User who does not have a Role. You should replace {{ $user->role->name }} with {{ !empty($user->role) ? $user->role->name:'' }}, like this:

    @foreach ($users as $user)
        <td>{{ $user->name }}</td>
        <td>{{ !empty($user->role) ? $user->role->name:'' }}</td>

Edit: You can use Laravel's the optional method to avoid errors (more information). For example:

    @foreach ($users as $user)
        <td>{{ $user->name }}</td>
        <td>{{ optional($user->role)->name }}</td>

If you are using PHP 8, you can use the null safe operator:

    @foreach ($users as $user)
        <td>{{ $user?->name }}</td>
        <td>{{ $user?->role?->name }}</td>

Jquery date picker z-index issue

Adding to Justin's answer, if you're worried about untidy markup or you don't want this value hard coded in CSS you can set the input before it is shown. Something like this:

            "position": "relative",
            "z-index": 20

Note that you cannot omit the "position": "relative" rule, as the plugin either looks in the inline style for both rules or the stylesheet, but not both.

The dialog("widget") is the actual datepicker that pops up.

How to get a list of column names on Sqlite3 database?

PRAGMA table_info(table_name);

will get you a list of all the column names.

Unable to Connect to For Cloning

Open port 9418 on your firewall - it's a custom port that Git uses to communicate on and it's often not open on a corporate or private firewall.

How to return the current timestamp with Moment.js?

Try this way:

moment().format('L');    // 05/25/2018
moment().format('l');    // 5/25/2018

Format Dates:

moment().format('MMMM Do YYYY, h:mm:ss a'); // May 25th 2018, 2:02:13 pm
moment().format('dddd');                    // Friday
moment().format("MMM Do YY");               // May 25th 18
moment().format('YYYY [escaped] YYYY');     // 2018 escaped 2018
moment().format();                          // 2018-05-25T14:02:13-05:00

Visit: for more info.

Get Cell Value from a DataTable in C#

If I have understood your question correctly you want to display one particular cell of your populated datatable? This what I used to display the given cell in my DataGrid.

var s  = dataGridView2.Rows[i].Cells[j].Value;
txt_Country.Text = s.ToString();

Hope this helps

Get column index from label in a data frame

Here is an answer that will generalize Henrik's answer.

df=data.frame(A=rnorm(100), B=rnorm(100), C=rnorm(100))
numeric_columns<-c('A', 'B', 'C')
numeric_index<-sapply(1:length(numeric_columns), function(i)
grep(numeric_columns[i], colnames(df))) 

How to check if array element is null to avoid NullPointerException in Java

Fighting whether the code is compiling or not I would say create a array of sixe 5 add 2 values and print them , you will get the two values and others are null. The question is although the size is 5 but there are 2 objects in the array . How to find how many objects are present in the array

Does C# have an equivalent to JavaScript's encodeURIComponent()?

You can use the Server object in the System.Web namespace

Server.UrlEncode, Server.UrlDecode, Server.HtmlEncode, and Server.HtmlDecode.

Edit: poster added that this was a windows application and not a web one as one would believe. The items listed above would be available from the HttpUtility class inside System.Web which must be added as a reference to the project.

Speed up rsync with Simultaneous/Concurrent File Transfers?

Have you tried using

With rclone you could do something like

rclone copy "${source}/${subfolder}/" "${target}/${subfolder}/" --progress --multi-thread-streams=N

where --multi-thread-streams=N represents the number of threads you wish to spawn.

Convert Pandas Series to DateTime in a DataFrame

df=pd.read_csv("filename.csv" , parse_dates=["<column name>"])

type(df.<column name>)

example: if you want to convert day which is initially a string to a Timestamp in Pandas

df=pd.read_csv("weather_data2.csv" , parse_dates=["day"])


The output will be pandas.tslib.Timestamp

Forwarding port 80 to 8080 using NGINX

As simple as like this,

make sure to change to your domain (or IP), and 8080 to your Node.js application port:

server {
    listen 80;

    location / {
        proxy_set_header   X-Forwarded-For $remote_addr;
        proxy_set_header   Host $http_host;
        proxy_pass         "";


What is the default maximum heap size for Sun's JVM from Java SE 6?

One can ask with some Java code:

long maxBytes = Runtime.getRuntime().maxMemory();
System.out.println("Max memory: " + maxBytes / 1024 / 1024 + "M");

See javadoc.

SQL Server IIF vs CASE

IIF is a non-standard T-SQL function. It was added to SQL SERVER 2012, so that Access could migrate to SQL Server without refactoring the IIF's to CASE before hand. Once the Access db is fully migrated into SQL Server, you can refactor.

How do I fix a "Performance counter registry hive consistency" when installing SQL Server R2 Express?

I had the perf counter reg issue and here's what I did.

  1. My exe file was SQLManagementStudio_x86_ENU.exe
  2. In command line typed in the below line and hit enter

C:\Projects\Installer\SQL Server 2008 Management Studio\SQLManagementStudio_x86_ENU.exe /ACTION=install /SKIPRULES=PerfMonCounterNotCorruptedCheck

(Note : i had the exe in this location of my machine C:\Projects\Installer\SQL Server 2008 Management Studio)

  1. SQL Server installation started and this time it skipped the rule for Perf counter registry values. The installation was successful.

How to get table cells evenly spaced?

You can use CSS. One way is to set table-layout to fixed, which stops the table and it's children from sizing according to their content. You can then set a fixed width on the relevant td elements. This should do the trick:

table.PerformanceTable {
    table-layout: fixed;
    width: 500px;
    table.PerformanceTable td.PerformanceCell {
        width: 75px;

Suggestions for for tidying up? You don't need the cellpadding or cellspacing attributes, or the TableRow and TableHeader classes. You can cover those off in CSS:

table {
    /* cellspacing */
    border-collapse: collapse;
    border-spacing: 0;
th {
    /* This covers the th elements */
tr {
    /* This covers the tr elements */
th, td {
    /* cellpadding */
    padding: 0;

You should use a heading (e.g. <h2>) instead of <span class="Emphasis"> and a <p> or a table <caption> instead of the Source <span>. You wouldn't need the <br> elements either, because you'd be using proper block level elements.

sql like operator to get the numbers only

You can use the following to only include valid characters:


WHERE Col NOT LIKE '%[^0-9.]%'



Detecting superfluous #includes in C/C++?

You can write a quick script that erases a single #include directive, compiles the projects, and logs the name in the #include and the file it was removed from in the case that no compilation errors occurred.

Let it run during the night, and the next day you will have a 100% correct list of include files you can remove.

Sometimes brute-force just works :-)

edit: and sometimes it doesn't :-). Here's a bit of information from the comments:

  1. Sometimes you can remove two header files separately, but not both together. A solution is to remove the header files during the run and not bring them back. This will find a list of files you can safely remove, although there might a solution with more files to remove which this algorithm won't find. (it's a greedy search over the space of include files to remove. It will only find a local maximum)
  2. There may be subtle changes in behavior if you have some macros redefined differently depending on some #ifdefs. I think these are very rare cases, and the Unit Tests which are part of the build should catch these changes.

Make the current commit the only (initial) commit in a Git repository?

The only solution that works for me (and keeps submodules working) is

git checkout --orphan newBranch
git add -A  # Add all files and commit them
git commit
git branch -D master  # Deletes the master branch
git branch -m master  # Rename the current branch to master
git push -f origin master  # Force push master branch to github
git gc --aggressive --prune=all     # remove the old files

Deleting .git/ always causes huge issues when I have submodules. Using git rebase --root would somehow cause conflicts for me (and take long since I had a lot of history).

Vue.js toggle class on click

If you don't need to access the toggle from outside the element, this code works without a data variable:

<a @click="e =>'active')"></a>

C# List<string> to string with delimiter

You can use String.Join. If you have a List<string> then you can call ToArray first:

List<string> names = new List<string>() { "John", "Anna", "Monica" };
var result = String.Join(", ", names.ToArray());

In .NET 4 you don't need the ToArray anymore, since there is an overload of String.Join that takes an IEnumerable<string>.


John, Anna, Monica

How to print something when running Puppet client?

Have you tried what is on the sample. I am new to this but here is the command: puppet --test --trace --debug. I hope this helps.

A required class was missing while executing org.apache.maven.plugins:maven-war-plugin:2.1.1:war

Does the class org.apache.maven.shared.filtering.MavenFilteringException exist in file:/C:/Users/utopcu/.m2/repository/org/apache/maven/shared/maven-filtering/1.0-beta-2/maven-filtering-1.0-beta-2.jar?

The error message suggests that it doesn't. Maybe the JAR was corrupted somehow.

I'm also wondering where the version 1.0-beta-2 comes from; I have 1.0 on my disk. Try version 2.3 of the WAR plugin.

Append key/value pair to hash with << in Ruby

Similar as they are, merge! and store treat existing hashes differently depending on keynames, and will therefore affect your preference. Other than that from a syntax standpoint, merge!'s key: "value" syntax closely matches up against JavaScript and Python. I've always hated comma-separating key-value pairs, personally.

hash = {}
hash.merge!(key: "value")
hash.merge!(:key => "value")
puts hash


hash = {}, "value")"key", "value")
puts hash

{:key=>"value", "key"=>"value"}

To get the shovel operator << working, I would advise using Mark Thomas's answer.

Caching a jquery ajax response in javascript/browser

I was looking for caching for my phonegap app storage and I found the answer of @TecHunter which is great but done using localCache.

I found and come to know that localStorage is another alternative to cache the data returned by ajax call. So, I created one demo using localStorage which will help others who may want to use localStorage instead of localCache for caching.

Ajax Call:

    type: "POST",
    dataType: 'json',
    contentType: "application/json; charset=utf-8",
    url: url,
    data: '{"Id":"' + Id + '"}',
    cache: true, //It must "true" if you want to cache else "false"
    //async: false,
    success: function (data) {
        var resData = JSON.parse(data);
        var Info = resData.Info;
        if (Info) {
            customerName = Info.FirstName;
    error: function (xhr, textStatus, error) {
        alert("Error Happened!");

To store data into localStorage:

$.ajaxPrefilter(function (options, originalOptions, jqXHR) {
if (options.cache) {
    var success = originalOptions.success || $.noop,
        url = originalOptions.url;

    options.cache = false; //remove jQuery cache as we have our own localStorage
    options.beforeSend = function () {
        if (localStorage.getItem(url)) {
            return false;
        return true;
    options.success = function (data, textStatus) {
        var responseData = JSON.stringify(data.responseJSON);
        localStorage.setItem(url, responseData);
        if ($.isFunction(success)) success(responseJSON); //call back to original ajax call

If you want to remove localStorage, use following statement wherever you want:


Hope it helps others!

Oracle - How to generate script from sql developer

This worked for me:

PL SQL Developer -> Tools -> Export User Objects

Select checkboxes: Include privilege and Include storage

Select your file name. Hit export.

You can later use generated export file to create table in another schema.

Find character position and update file name

The string is a .NET string so you can use .NET methods. In your case:

$index = "The string".IndexOf(" ")

will return 3, which is the first occurrence of space in the string. For more information see:

For your need try something like:

$s.SubString($s.IndexOf("_") + 1, $s.LastIndexOf(".") - $s.IndexOf("_") - 1)

Or you could use regexps:

if ($s -Match '(_)(.*)(\.)[^.]*$') {  $matches[2] }

(has to be adjusted depending on exactly what you need).

Adding items to an object through the .push() method

.push() is a method of the Built-in Array Object

It is not related to jQuery in any way.

You are defining a literal Object with

// Object
var stuff = {};

You can define a literal Array like this

// Array
var stuff = [];



Arrays actually get their bracket syntax stuff[index] inherited from their parent, the Object. This is why you are able to use it the way you are in your first example.

This is often used for effortless reflection for dynamically accessing properties

stuff = {}; // Object

stuff['prop'] = 'value'; // assign property of an 
                         // Object via bracket syntax

stuff.prop === stuff['prop']; // true

ERROR 2003 (HY000): Can't connect to MySQL server (111)

/etc/mysql$ sudo nano my.cnf

Relevant portion that works for me:

# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address            = MY_IP

MY_IP can be found using ifconfig or curl -L |grep blue.

Restart mysql to ensure the new config is loaded:

/etc/mysql$ sudo service mysql restart

Parse usable Street Address, City, State, Zip from a string

There are data services that given a zip code will give you list of street names in that zip code.

Use a regex to extract Zip or City State - find the correct one or if a error get both. pull the list of streets from a data source Correct the city and state, and then street address. Once you get a valid Address line 1, city, state, and zip you can then make assumptions on address line 2..3

Passing arguments to "make run"

I don't know a way to do what you want exactly, but a workaround might be:

run: ./prog
    ./prog $(ARGS)


make ARGS="asdf" run
# or
make run ARGS="asdf"

Java: Date from unix timestamp

Date d = new Date(i * 1000 + TimeZone.getDefault().getRawOffset());

Jenkins not executing jobs (pending - waiting for next executor)

In my case, I had the following set in my JenkinsFile

node('node'){ ... }

There was no node called 'node', only master (the value had been left in there after following some basic tutorials). Changing the value to 'master' got the build working.

HTML.HiddenFor value set

Strange but, Try with @Value , capital "V"

e.g. (working on MVC4)

@Html.HiddenFor(m => m.Id, new { @Value = Model.Id })


Found that @Value (capital V) is creating another attribute with "Value" along with "value", using small @value seems to be working too!

Need to check the MVC source code to find more.

Update, After going through how it works internally:

First of all forget all these workarounds (I have kept in for the sake of continuity here), now looks silly :)

Basically, it happens when a model is posted and the model is returned back to same page.

The value is accessed (and formed into html) in InputHelper method (InputExtensions.cs) using following code fragment

string attemptedValue = (string)htmlHelper.GetModelStateValue(fullName, typeof(string));

The GetModelStateValue method (in Htmlelper.cs) retrieves the value as

ViewData.ModelState.TryGetValue(key, out modelState)

Here is the issue, since the value is accessed from ViewData.ModelState dictionary. This returns the value posted from the page instead of modified value!!

i.e. If your posted value of the variable (e.g. Person.Id) is 0 but you set the value inside httpPost action (e.g. Person.Id = 2), the ModelState still retains the old value "0" and the attemptedValue contains "0" ! so the field in rendered page will contain "0" as value!!

Workaround if you are returning model to same page : Clear the item from ModelState,



This will remove the item from dictionary and the ViewData.ModelState.TryGetValue(key, out modelState) returns null, and the next statement (inside InputExtensions.cs) takes the actual value (valueParameter) passed to HiddenFor(m => m.Id)

this is done in the following line in InputExtensions.cs

tagBuilder.MergeAttribute("value", attemptedValue ?? ((useViewData) ? htmlHelper.EvalString(fullName, format) : valueParameter), isExplicitValue);


Clear the item in ModelState using:


Hope this is helpful.

Change MySQL default character set to UTF-8 in my.cnf?

This question already has a lot of answers, but Mathias Bynens mentioned that 'utf8mb4' should be used instead of 'utf8' in order to have better UTF-8 support ('utf8' does not support 4 byte characters, fields are truncated on insert). I consider this to be an important difference. So here is yet another answer on how to set the default character set and collation. One that'll allow you to insert a pile of poo ().

This works on MySQL 5.5.35.

Note, that some of the settings may be optional. As I'm not entirely sure that I haven't forgotten anything, I'll make this answer a community wiki.

Old Settings

mysql> SHOW VARIABLES LIKE 'char%'; SHOW VARIABLES LIKE 'collation%';
| Variable_name            | Value                      |
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | latin1                     |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | latin1                     |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
8 rows in set (0.00 sec)

| Variable_name        | Value             |
| collation_connection | utf8_general_ci   |
| collation_database   | latin1_swedish_ci |
| collation_server     | latin1_swedish_ci |
3 rows in set (0.00 sec)


# UTF-8 should be used instead of Latin1. Obviously.
# NOTE "utf8" in MySQL is NOT full UTF-8:

default-character-set = utf8mb4

character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci

default-character-set = utf8mb4

New Settings

mysql> SHOW VARIABLES LIKE 'char%'; SHOW VARIABLES LIKE 'collation%';
| Variable_name            | Value                      |
| character_set_client     | utf8mb4                    |
| character_set_connection | utf8mb4                    |
| character_set_database   | utf8mb4                    |
| character_set_filesystem | binary                     |
| character_set_results    | utf8mb4                    |
| character_set_server     | utf8mb4                    |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
8 rows in set (0.00 sec)

| Variable_name        | Value              |
| collation_connection | utf8mb4_general_ci |
| collation_database   | utf8mb4_unicode_ci |
| collation_server     | utf8mb4_unicode_ci |
3 rows in set (0.00 sec)

character_set_system is always utf8.

This won't affect existing tables, it's just the default setting (used for new tables). The following ALTER code can be used to convert an existing table (without the dump-restore workaround):

ALTER DATABASE databasename CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE tablename CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;


On a MySQL 5.0 server: character_set_client, character_set_connection, character_set_results, collation_connection remain at latin1. Issuing SET NAMES utf8 (utf8mb4 not available in that version) sets those to utf8 as well.

Caveat: If you had a utf8 table with an index column of type VARCHAR(255), it can't be converted in some cases, because the maximum key length is exceeded (Specified key was too long; max key length is 767 bytes.). If possible, reduce the column size from 255 to 191 (because 191 * 4 = 764 < 767 < 192 * 4 = 768). After that, the table can be converted.

Determine when a ViewPager changes pages

ViewPager.setOnPageChangeListener is deprecated now. You now need to use ViewPager.addOnPageChangeListener instead.

for example,

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {


        public void onPageSelected(int position) {


        public void onPageScrollStateChanged(int state) {


How to enter a series of numbers automatically in Excel


Using formula

  1. Paste the above formula in column A or where you need to have the serial no
  2. When the second column (For Example, when B column is filled the serial no will be automatically generated in column A).

Declaring variable workbook / Worksheet vba

Dim ws as Object

Set ws = Worksheets("name")

when declaring the worksheet as worksheet instead of an ojbect I had issues working with OptionButtons (Active X) in this worksheet (I guess the same will be with any Active-X element. When declared as object everything works fine.

How to update an "array of objects" with Firestore?

We can use arrayUnion({}) method to achive this.

Try this:

    sharedWith: admin.firestore.FieldValue.arrayUnion({
       who: "[email protected]",
       when: new Date()

Documentation can find here:

Change Text Color of Selected Option in a Select Box


<select id="sel" onclick="document.getElementById('sel').style.color='green';">
 <option>Select Your Option</option>
 <option value="">INDIA</option>
 <option value="">USA</option>

The above code will change the colour of text on click of the select box.

and if you want every option different colour, give separate class or id to all options.

How to show full height background image?

This worked for me (though it's for reactjs & tachyons used as inline CSS)

<div className="pa2 cf vh-100-ns" style={{backgroundImage: `url(${a6})`}}> 

This takes in css as height: 100vh

Variable might not have been initialized error

It's a good practice to initialize the local variables inside the method block before using it. Here is a mistake that a beginner may commit.

  public static void main(String[] args){
    int a;
    int[] arr = {1,2,3,4,5};
    for(int i=0; i<arr.length; i++){
        a = arr[i];

You may expect the console will show '5' but instead the compiler will throw 'variable a might not be initialized' error. Though one may think variable a is 'initialized' inside the for loop, the compiler does not think in that way. What if arr.length is 0? The for loop will not be run at all. Hence, the compiler will give variable a might not have been initialized to point out the potential danger and require you to initialize the variable.

To prevent this kind of error, just initialize the variable when you declare it.

int a = 0;

Java String split removed empty values

you may have multiple separators, including whitespace characters, commas, semicolons, etc. take those in repeatable group with []+, like:

 String[] tokens = "a , b,  ,c; ;d,      ".split( "[,; \t\n\r]+" );

you'll have 4 tokens -- a, b, c, d

leading separators in the source string need to be removed before applying this split.

as answer to question asked:

String data = "5|6|7||8|9||";
String[] split = data.split("[\\| \t\n\r]+");

whitespaces added just in case if you'll have those as separators along with |

Scripting Language vs Programming Language

I think that what you are stating as the "difference" is actually a consequence of the real difference.

The actual difference is the target of the code written. Who is going to run this code.

A scripting language is used to write code that is going to target a software system. It's going to automate operations on that software system. The script is going to be a sequence of instructions to the target software system.

A programming language targets the computing system, which can be a real or virtual machine. The instructions are executed by the machine.

Of course, a real machine understands only binary code so you need to compile the code of a programming language. But this is a consequence of targeting a machine instead of a program.

In the other hand, the target software system of an script may compile the code or interpret it. Is up to the software system.

If we say that the real difference is whether it is compiled or not, then we have a problem because when Javascript runs in V8 is compiled and when it runs in Rhino is not.

It gets more confusing since scripting languages have evolved to become very powerful. So they are not limited to create small scripts to automate operations on another software system, you can create any rich applications with them.

Python code targets an interpreter so we can say that it "scripts" operations on that interpreter. But when you write Python code you don't see it as scripting an interpreter, you see it as creating an application. The interpreter is just there to code at a higher level among other things. So for me Python is more a programming language than an scripting language.

How to set cursor position in EditText?

some time edit text cursor donot comes at particular position is if we directly use editText.setSelection(position); . In that case you can try Runnable() {
                public void run() {

How to throw RuntimeException ("cannot find symbol")

throw new RuntimeException(msg);

You need the new in there. It's creating an instance and throwing it, not calling a method.

Using Math.round to round to one decimal place?

try this

for example

DecimalFormat df = new DecimalFormat("#.##");



Windows command to get service status?

Ros the code i post also is for knowing how many services are running...

Imagine you want to know how many services are like Oracle* then you put Oracle instead of NameOfSercive... and you get the number of services like Oracle* running on the variable %CountLines% and if you want to do something if there are only 4 you can do something like this:

IF 4==%CountLines% GOTO FourServicesAreRunning

That is much more powerfull... and your code does not let you to know if desired service is running ... if there is another srecive starting with same name... imagine: -ServiceOne -ServiceOnePersonal

If you search for ServiceOne, but it is only running ServiceOnePersonal your code will tell ServiceOne is running...

My code can be easly changed, since it reads all lines of the file and read line by line it can also do whatever you want to each service... see this:

REM Put here any code to be run before check for Services

SET TemporalFile=TemporalFile.TXT
NET START > %TemporalFile%
SET CountLines=0
FOR /F "delims=" %%X IN (%TemporalFile%) DO SET /A CountLines=1+CountLines
SETLOCAL EnableDelayedExpansion
SET CountLine=0
FOR /F "delims=" %%X IN (%TemporalFile%) DO @(
 SET /A CountLine=1+CountLine

 REM Do whatever you want to each line here, remember first and last are special not service names

 IF 1==!CountLine! (

   REM Do whatever you want with special first line, not a service.

 ) ELSE IF %CountLines%==!CountLine! (

   REM Do whatever you want with special last line, not a service.

 ) ELSE (

   REM Do whatever you want with rest lines, for each service.
   REM    For example echo its position number and name:

   echo !CountLine! - %%X

   REM    Or filter by exact name (do not forget to not remove the three spaces at begining):
   IF "   NameOfService"=="%%X" (

     REM Do whatever you want with Service filtered.


 REM Do whatever more you want to all lines here, remember two first are special as last one


DEL -P %TemporalFile% 2>nul
SET TemporalFile=

REM Put here any code to be run after check for Services

Of course it only list running services, i do not know any way net can list not running services...

Hope this helps!!!

How to escape strings in SQL Server using PHP?

You could roll your own version of mysql_real_escape_string, (and improve upon it) with the following regular expression: [\000\010\011\012\015\032\042\047\134\140]. That takes care of the following characters: null, backspace, horizontal tab, new line, carriage return, substitute, double quote, single quote, backslash, grave accent. Backspace and horizontal tab are not supported by mysql_real_escape_string.

What exactly does Double mean in java?

In a comment on @paxdiablo's answer, you asked:

"So basically, is it better to use Double than Float?"

That is a complicated question. I will deal with it in two parts

Deciding between double versus float

On the one hand, a double occupies 8 bytes versus 4 bytes for a float. If you have many of them, this may be significant, though it may also have no impact. (Consider the case where the values are in fields or local variables on a 64bit machine, and the JVM aligns them on 64 bit boundaries.) Additionally, floating point arithmetic with double values is typically slower than with float values ... though once again this is hardware dependent.

On the other hand, a double can represent larger (and smaller) numbers than a float and can represent them with more than twice the precision. For the details, refer to Wikipedia.

The tricky question is knowing whether you actually need the extra range and precision of a double. In some cases it is obvious that you need it. In others it is not so obvious. For instance if you are doing calculations such as inverting a matrix or calculating a standard deviation, the extra precision may be critical. On the other hand, in some cases not even double is going to give you enough precision. (And beware of the trap of expecting float and double to give you an exact representation. They won't and they can't!)

There is a branch of mathematics called Numerical Analysis that deals with the effects of rounding error, etc in practical numerical calculations. It used to be a standard part of computer science courses ... back in the 1970's.

Deciding between Double versus Float

For the Double versus Float case, the issues of precision and range are the same as for double versus float, but the relative performance measures will be slightly different.

  • A Double (on a 32 bit machine) typically takes 16 bytes + 4 bytes for the reference, compared with 12 + 4 bytes for a Float. Compare this to 8 bytes versus 4 bytes for the double versus float case. So the ratio is 5 to 4 versus 2 to 1.

  • Arithmetic involving Double and Float typically involves dereferencing the pointer and creating a new object to hold the result (depending on the circumstances). These extra overheads also affect the ratios in favor of the Double case.


Having said all that, the most important thing is correctness, and this typically means getting the most accurate answer. And even if accuracy is not critical, it is usually not wrong to be "too accurate". So, the simple "rule of thumb" is to use double in preference to float, UNLESS there is an overriding performance requirement, AND you have solid evidence that using float will make a difference with respect to that requirement.

How to resolve a Java Rounding Double issue

It's quite simple.

Use the %.2f operator for output. Problem solved!

For example:

int a = 877.8499999999999;
System.out.printf("Formatted Output is: %.2f", a);

The above code results in a print output of: 877.85

The %.2f operator defines that only TWO decimal places should be used.

How to prevent buttons from submitting forms

Suppose your HTML form has id="form_id"

<form id="form_id">
<!--your HTML code-->

Add this jQuery snippet to your code to see result,

  return false;

In Python how should I test if a variable is None, True or False

Never, never, never say

if something == True:

Never. It's crazy, since you're redundantly repeating what is redundantly specified as the redundant condition rule for an if-statement.

Worse, still, never, never, never say

if something == False:

You have not. Feel free to use it.

Finally, doing a == None is inefficient. Do a is None. None is a special singleton object, there can only be one. Just check to see if you have that object.

How do I encrypt and decrypt a string in python?

You may use Fernet as follows:

from cryptography.fernet import Fernet
key = Fernet.generate_key()
f = Fernet(key)
encrypt_value = f.encrypt(b"YourString")

Init array of structs in Go

You can have it this way:

It is important to mind the commas after each struct item or set of items.

earnings := []LineItemsType{


            TypeName: "Earnings",

            Totals: 0.0,

            HasTotal: true,

            items: []LineItems{


                    name: "Basic Pay",

                    amount: 100.0,


                    name: "Commuter Allowance",

                    amount: 100.0,

            TypeName: "Earnings",

            Totals: 0.0,

            HasTotal: true,

            items: []LineItems{


                    name: "Basic Pay",

                    amount: 100.0,


                    name: "Commuter Allowance",

                    amount: 100.0,

How to add chmod permissions to file in Git?

Antwane's answer is correct, and this should be a comment but comments don't have enough space and do not allow formatting. :-) I just want to add that in Git, file permissions are recorded only1 as either 644 or 755 (spelled (100644 and 100755; the 100 part means "regular file"):

diff --git a/path b/path
new file mode 100644

The former—644—means that the file should not be executable, and the latter means that it should be executable. How that turns into actual file modes within your file system is somewhat OS-dependent. On Unix-like systems, the bits are passed through your umask setting, which would normally be 022 to remove write permission from "group" and "other", or 002 to remove write permission only from "other". It might also be 077 if you are especially concerned about privacy and wish to remove read, write, and execute permission from both "group" and "other".

1Extremely-early versions of Git saved group permissions, so that some repositories have tree entries with mode 664 in them. Modern Git does not, but since no part of any object can ever be changed, those old permissions bits still persist in old tree objects.

The change to store only 0644 or 0755 was in commit e44794706eeb57f2, which is before Git v0.99 and dated 16 April 2005.

forward declaration of a struct in C?

A struct (without a typedef) often needs to (or should) be with the keyword struct when used.

struct A;                      // forward declaration
void function( struct A *a );  // using the 'incomplete' type only as pointer

If you typedef your struct you can leave out the struct keyword.

typedef struct A A;          // forward declaration *and* typedef
void function( A *a );

Note that it is legal to reuse the struct name

Try changing the forward declaration to this in your code:

typedef struct context context;

It might be more readable to do add a suffix to indicate struct name and type name:

typedef struct context_s context_t;

Difference between a Seq and a List in Scala

As @daniel-c-sobral said, List extends the trait Seq and is an abstract class implemented by scala.collection.immutable.$colon$colon (or :: for short), but technicalities aside, mind that most of lists and seqs we use are initialized in the form of Seq(1, 2, 3) or List(1, 2, 3) which both return scala.collection.immutable.$colon$colon, hence one can write:

var x: scala.collection.immutable.$colon$colon[Int] = null
x = Seq(1, 2, 3).asInstanceOf[scala.collection.immutable.$colon$colon[Int]]
x = List(1, 2, 3).asInstanceOf[scala.collection.immutable.$colon$colon[Int]]

As a result, I'd argue than the only thing that matters are the methods you want to expose, for instance to prepend you can use :: from List that I find redundant with +: from Seq and I personally stick to Seq by default.

Set height of chart in Chart.js

Just to add on to the answer given by @numediaweb

In case you're banging your head against the wall because after following the instructions to set maintainAspectRatio=false: I originally copied my code from an example I got on a website on using Chart.js with Angular 2+:

        <div style="display: block">
          <canvas baseChart

To make this work correctly you must remove the embedded (and unnecessary) style="display: block" Instead define a class for the enclosing div, and define its height in CSS.

Once you do that, the chart should have responsive width but fixed height.

Foreign key referencing a 2 columns primary key in SQL Server

Of course it's possible to create a foreign key relationship to a compound (more than one column) primary key. You didn't show us the statement you're using to try and create that relationship - it should be something like:

ALTER TABLE dbo.Content
   ADD CONSTRAINT FK_Content_Libraries
   FOREIGN KEY(LibraryID, Application)
   REFERENCES dbo.Libraries(ID, Application)

Is that what you're using?? If (ID, Application) is indeed the primary key on dbo.Libraries, this statement should definitely work.

Luk: just to check - can you run this statement in your database and report back what the output is??

    tc.TABLE_NAME IN ('Libraries', 'Content')

How to set custom ActionBar color / style?

For Android 3.0 and higher only

When supporting Android 3.0 and higher only, you can define the action bar's background like this:


<?xml version="1.0" encoding="utf-8"?>
    <!-- the theme applied to the application or activity -->
    <style name="CustomActionBarTheme" parent="@style/Theme.Holo.Light.DarkActionBar">
       <item name="android:actionBarStyle">@style/MyActionBar</item>

<!-- ActionBar styles -->
  <style name="MyActionBar" parent="@style/Widget.Holo.Light.ActionBar.Solid.Inverse">
       <item name="android:background">#ff0000</item>

For Android 2.1 and higher

When using the Support Library, your style XML file might look like this:

<?xml version="1.0" encoding="utf-8"?>
  <!-- the theme applied to the application or activity -->
 <style name="CustomActionBarTheme" parent="@style/Theme.AppCompat.Light.DarkActionBar">
    <item name="android:actionBarStyle">@style/MyActionBar</item>

    <!-- Support library compatibility -->
    <item name="actionBarStyle">@style/MyActionBar</item>

<!-- ActionBar styles -->
<style name="MyActionBar"
    <item name="android:background">@drawable/actionbar_background</item>

    <!-- Support library compatibility -->
    <item name="background">@drawable/actionbar_background</item>

Then apply your theme to your entire app or individual activities:

for more details Documentaion

How to delete from a text file, all lines that contain a specific string?

echo -e "/thing_to_delete\ndd\033:x\n" | vim file_to_edit.txt

How do I rotate text in css?

You can use like this...

<div id="rot">hello</div>

   -webkit-transform: rotate(-90deg); 
   -moz-transform: rotate(-90deg);    

Have a look at this fiddle:

Cleanest way to build an SQL string in Java

Why do you want to generate all the sql by hand? Have you looked at an ORM like Hibernate Depending on your project it will probably do at least 95% of what you need, do it in a cleaner way then raw SQL, and if you need to get the last bit of performance you can create the SQL queries that need to be hand tuned.

How to solve ADB device unauthorized in Android ADB host device?

I found one solution with Nexus 5, and TWRP installed. Basically format was the only solution I found and I tried all solutions listed here before: ADB Android Device Unauthorized

Ask Google to make backup of your apps. Save all important files you may have on your phone

Please note that I decline all liability in case of failure as what I did was quite risky but worked in my case:

Enable USB debugging in developer option (not sure if it helped as device was unauthorized but still...)

Make sure your phone is connected to computer and you can access storage

Download google img of your nexus: unrar your files and places them in a new folder on your computer, name it factory (any name will do).

wipe ALL datas... you will have 0 file in your android accessed from computer.

Then reboot into BOOTLOADER mode... you will have the message "you have no OS installed are you sure you want to reboot ?"

Then execute (double click) the .bat file inside the "factory" folder.

You will see command line detailed installation of the OS. Of course avoid disconnecting cable during this phase...

Phone will take about 5mn to initialize.

Does Index of Array Exist

The answers here are straightforward but only apply to a 1 dimensional array. For multi-dimensional arrays, checking for null is a straightforward way to tell if the element exists. Example code here checks for null. Note the try/catch block is [probably] overkill but it makes the block bomb-proof.

public ItemContext GetThisElement(int row,
    int col)
    ItemContext ctx = null;
    if (rgItemCtx[row, col] != null)
          ctx = rgItemCtx[row, col];
        catch (SystemException sex)
          ctx = null;
          // perhaps do something with sex properties

    return (ctx);

How do I associate file types with an iPhone application?

In addition to Brad's excellent answer, I have found out that (on iOS 4.2.1 at least) when opening custom files from the Mail app, your app is not fired or notified if the attachment has been opened before. The "open with…" popup appears, but just does nothing.

This seems to be fixed by (re)moving the file from the Inbox directory. A safe approach seems to be to both (re)move the file as it is opened (in -(BOOL)application:openURL:sourceApplication:annotation:) as well as going through the Documents/Inbox directory, removing all items, e.g. in applicationDidBecomeActive:. That last catch-all may be needed to get the app in a clean state again, in case a previous import causes a crash or is interrupted.

C# DropDownList with a Dictionary as DataSource

If the DropDownList is declared in your aspx page and not in the codebehind, you can do it like this.


<asp:DropDownList ID="ddlStatus" runat="server" DataSource="<%# Statuses %>"
     DataValueField="Key" DataTextField="Value"></asp:DropDownList>


protected void Page_Load(object sender, EventArgs e)
    // or use Page.DataBind() to bind everything

public Dictionary<int, string> Statuses
        // do database/webservice lookup here to populate Dictionary

Attach Authorization header for all axios requests

Similarly, we have a function to set or delete the token from calls like this:

import axios from 'axios';

export default function setAuthToken(token) {
  axios.defaults.headers.common['Authorization'] = '';
  delete axios.defaults.headers.common['Authorization'];

  if (token) {
    axios.defaults.headers.common['Authorization'] = `${token}`;

We always clean the existing token at initialization, then establish the received one.

How to set image for bar button with swift?

Your problem is because of the way the icon has been made - it doesn't conform to Apple's custom tab bar icon specs:

To design a custom bar icon, follow these guidelines:

  • Use pure white with appropriate alpha transparency.
  • Don’t include a drop shadow.
  • Use antialiasing.

(From the guidelines.)

Something that would be possible looks like this. You can find such icons on most free tab bar icon sites.

Button example

Is background-color:none valid CSS?

.class {

This is not a valid property. W3C validator will display following error:

Value Error : background-color none is not a background-color value : none

transparent may have been selected as better term instead of 0 or none values during the development of specification of CSS.

How to dismiss the dialog with click on outside of the dialog?

This method should completely avoid activities below the grey area retrieving click events.

Remove this line if you have it:

window.setFlags(WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL, WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL);

Put this on your activity created

getWindow().setFlags(LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH, LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH);

then override the touch event with this

public boolean onTouchEvent(MotionEvent ev)
    if(MotionEvent.ACTION_DOWN == ev.getAction())
        Rect dialogBounds = new Rect();
        if (!dialogBounds.contains((int) ev.getX(), (int) ev.getY())) {
            // You have clicked the grey area
            return false; // stop activity closing

    // Touch events inside are fine.
    return super.onTouchEvent(ev);

Vagrant ssh authentication failure

First of all you should remove the autogenerated insecure_private_key file, then regenerate this file by typing

vagrant ssh-config


vagrant halt
vagrant up

It should work

How to hide axes and gridlines in Matplotlib (python)

# Hide grid lines

# Hide axes ticks

Note, you need matplotlib>=1.2 for set_zticks() to work.

How to restart remote MySQL server running on Ubuntu linux?

sudo service mysql stop;
sudo service mysql start;

If the above process will not work let's check one the given code above you can stop Mysql server and again start server

How to get resources directory path programmatically



File folder = new ClassPathResource("sql").getFile();
File[] listOfFiles = folder.listFiles();

It is worth noting that this will limit your deployment options, ClassPathResource.getFile() only works if the container has exploded (unzipped) your war file.

How do I print the type or class of a variable in Swift?

Xcode 8 Swift 3.0 use type(of:)

let className = "\(type(of: instance))"

Evaluating a mathematical expression in a string

[I know this is an old question, but it is worth pointing out new useful solutions as they pop up]

Since python3.6, this capability is now built into the language, coined "f-strings".

See: PEP 498 -- Literal String Interpolation

For example (note the f prefix):

=> '16'

Custom thread pool in Java 8 parallel stream

Go to get AbacusUtil. Thread number can by specified for parallel stream. Here is the sample code:

LongStream.range(4, 1_000_000).parallel(threadNum)...

Disclosure: I'm the developer of AbacusUtil.

How do I delete all messages from a single queue using the CLI?

In order to delete only messages from the queue use :

sudo rabbitmqctl --node <nodename> purge_queue <queue_name>

In order to delete a queue which is empty(--if-empty) or has no consumers(--if-unused) use :

sudo rabbitmqctl --node <nodename> delete_queue <queue_name> --if-empty


sudo rabbitmqctl --node <nodename> delete_queue <queue_name> --if-unused 

How do I define a method in Razor?

It's very simple to define a function inside razor.

@functions {

    public static HtmlString OrderedList(IEnumerable<string> items)
    { }

So you can call a the function anywhere. Like

@Functions.OrderedList(new[] { "Blue", "Red", "Green" })

However, this same work can be done through helper too. As an example

@helper OrderedList(IEnumerable<string> items){
        @foreach(var item in items){

So what is the difference?? According to this previous post both @helpers and @functions do share one thing in common - they make code reuse a possibility within Web Pages. They also share another thing in common - they look the same at first glance, which is what might cause a bit of confusion about their roles. However, they are not the same. In essence, a helper is a reusable snippet of Razor sytnax exposed as a method, and is intended for rendering HTML to the browser, whereas a function is static utility method that can be called from anywhere within your Web Pages application. The return type for a helper is always HelperResult, whereas the return type for a function is whatever you want it to be.

How to remove a branch locally?

You can delete multiple branches on windows using Git GUI:

  1. Go to your Project folder
  2. Open Git Gui: enter image description here
  3. Click on 'Branch': enter image description here
  4. Now choose 'Delete': enter image description here
  5. If you want to delete all branches besides the fact they are merged or not, then check 'Always (Do not perform merge checks)' enter image description here

line breaks in a textarea

What I found works in the form is str_replace('&lt;br&gt;', PHP_EOL, $textarea);

How to switch to new window in Selenium for Python?

for eg. you may take


since, it is a current window ,we can name it

main_page = driver.current_window_handle

if there are atleast 1 window popup except the current window,you may try this method and put if condition in break statement by hit n trial for the index

for handle in driver.window_handles:
    if handle != main_page:
        login_page = handle


Now ,whatever the credentials you have to apply,provide after it is loggen in. Window will disappear, but you have to come to main page window and you are done


How to vertically center content with variable height within a div?

Best result for me so far:

div to be centered:

position: absolute;
top: 50%;
transform: translateY(-50%);
margin: 0 auto;
right: 0;
left: 0;

Using SUMIFS with multiple AND OR conditions


SUMPRODUCT is faster than SUM arrays, i.e. having {} arrays in the SUM function. SUMIFS is 30% faster than SUMPRODUCT.

{SUM(SUMIFS({}))} vs SUMPRODUCT(SUMIFS({})) both works fine, but SUMPRODUCT feels a bit easier to write without the CTRL-SHIFT-ENTER to create the {}.


I personally prefer writing SUMPRODUCT(--(ISNUMBER(MATCH(...)))) over SUMPRODUCT(SUMIFS({})) for multiple criteria.

However, if you have a drop-down menu where you want to select specific characteristics or all, SUMPRODUCT(SUMIFS()), is the only way to go. (as for selecting "all", the value should enter in "<>" + "Whatever word you want as long as it's not part of the specific characteristics".

Not equal string

It should be this:

if (myString!="-1")
//Do things

Your equals and exclamation are the wrong way round.

How to present UIActionSheet iOS Swift?

Swift 3 For displaying UIAlertController from UIBarButtonItem on iPad

        let alert = UIAlertController(title: "Title", message: "Please Select an Option", preferredStyle: .actionSheet)

    alert.addAction(UIAlertAction(title: "Approve", style: .default , handler:{ (UIAlertAction)in
        print("User click Approve button")

    alert.addAction(UIAlertAction(title: "Edit", style: .default , handler:{ (UIAlertAction)in
        print("User click Edit button")

    alert.addAction(UIAlertAction(title: "Delete", style: .destructive , handler:{ (UIAlertAction)in
        print("User click Delete button")

    alert.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.cancel, handler:{ (UIAlertAction)in
        print("User click Dismiss button")

    if let presenter = alert.popoverPresentationController {
        presenter.barButtonItem = sender

    self.present(alert, animated: true, completion: {
        print("completion block")

Remove array element based on object property

jAndy's solution is probably best, but if you can't rely on filter you could do something like:

var myArray = [
    {field: 'id', operator: 'eq', value: 'id'}, 
    {field: 'cStatus', operator: 'eq', value: 'cStatus'}, 
    {field: 'money', operator: 'eq', value: "money"}

myArray.remove_key = function(key){
    var i = 0, 
        keyval = null;
    for( ; i < this.length; i++){
        if(this[i].field == key){
            keyval = this.splice(i, 1);
    return keyval;

Adding quotes to a string in VBScript

You can escape by doubling the quotes

g="abcd """ & a & """"

or write an explicit chr() call

g="abcd " & chr(34) & a & chr(34)

How do I push a local Git branch to master branch in the remote?

As an extend to @Eugene's answer another version which will work to push code from local repo to master/develop branch .

Switch to branch ‘master’:

$ git checkout master

Merge from local repo to master:

$ git merge --no-ff FEATURE/<branch_Name>

Push to master:

$ git push

Convert IEnumerable to DataTable

Firstly you need to add a where T:class constraint - you can't call GetValue on value types unless they're passed by ref.

Secondly GetValue is very slow and gets called a lot.

To get round this we can create a delegate and call that instead:

MethodInfo method = property.GetGetMethod(true);
Delegate.CreateDelegate(typeof(Func<TClass, TProperty>), method );

The problem is that we don't know TProperty, but as usual on here Jon Skeet has the answer - we can use reflection to retrieve the getter delegate, but once we have it we don't need to reflect again:

public class ReflectionUtility
    internal static Func<object, object> GetGetter(PropertyInfo property)
        // get the get method for the property
        MethodInfo method = property.GetGetMethod(true);

        // get the generic get-method generator (ReflectionUtility.GetSetterHelper<TTarget, TValue>)
        MethodInfo genericHelper = typeof(ReflectionUtility).GetMethod(
            BindingFlags.Static | BindingFlags.NonPublic);

        // reflection call to the generic get-method generator to generate the type arguments
        MethodInfo constructedHelper = genericHelper.MakeGenericMethod(

        // now call it. The null argument is because it's a static method.
        object ret = constructedHelper.Invoke(null, new object[] { method });

        // cast the result to the action delegate and return it
        return (Func<object, object>) ret;

    static Func<object, object> GetGetterHelper<TTarget, TResult>(MethodInfo method)
        where TTarget : class // target must be a class as property sets on structs need a ref param
        // Convert the slow MethodInfo into a fast, strongly typed, open delegate
        Func<TTarget, TResult> func = (Func<TTarget, TResult>) Delegate.CreateDelegate(typeof(Func<TTarget, TResult>), method);

        // Now create a more weakly typed delegate which will call the strongly typed one
        Func<object, object> ret = (object target) => (TResult) func((TTarget) target);
        return ret;

So now your method becomes:

public static DataTable ToDataTable<T>(this IEnumerable<T> items) 
    where T: class
    // ... create table the same way

    var propGetters = new List<Func<T, object>>();
foreach (var prop in props)
        Func<T, object> func = (Func<T, object>) ReflectionUtility.GetGetter(prop);

    // Add the property values per T as rows to the datatable
    foreach (var item in items) 
        var values = new object[props.Length];  
        for (var i = 0; i < props.Length; i++) 
            //values[i] = props[i].GetValue(item, null);   
            values[i] = propGetters[i](item);


    return table; 

You could further optimise it by storing the getters for each type in a static dictionary, then you will only have the reflection overhead once for each type.

Makefile to compile multiple C programs?

This will compile all *.c files upon make to executables without the .c extension as in gcc program.c -o program.

make will automatically add any flags you add to CFLAGS like CFLAGS = -g Wall.

If you don't need any flags CFLAGS can be left blank (as below) or omitted completely.

SOURCES = $(wildcard *.c)
EXECS = $(SOURCES:%.c=%)

all: $(EXECS)

Java LinkedHashMap get first or last entry

I know that I came too late but I would like to offer some alternatives, not something extraordinary but some cases that none mentioned here. In case that someone doesn't care so much for efficiency but he wants something with more simplicity(perhaps find the last entry value with one line of code), all this will get quite simplified with the arrival of Java 8 . I provide some useful scenarios.

For the sake of the completeness, I compare these alternatives with the solution of arrays that already mentioned in this post by others users. I sum up all the cases and i think they would be useful(when performance does matter or no) especially for new developers, always depends on the matter of each problem

Possible Alternatives

Usage of Array Method

I took it from the previous answer to to make the follow comparisons. This solution belongs @feresr.

  public static String FindLasstEntryWithArrayMethod() {
        return String.valueOf(linkedmap.entrySet().toArray()[linkedmap.size() - 1]);

Usage of ArrayList Method

Similar to the first solution with a little bit different performance

public static String FindLasstEntryWithArrayListMethod() {
        List<Entry<Integer, String>> entryList = new ArrayList<Map.Entry<Integer, String>>(linkedmap.entrySet());
        return entryList.get(entryList.size() - 1).getValue();

Reduce Method

This method will reduce the set of elements until getting the last element of stream. In addition, it will return only deterministic results

public static String FindLasstEntryWithReduceMethod() {
        return linkedmap.entrySet().stream().reduce((first, second) -> second).orElse(null).getValue();

SkipFunction Method

This method will get the last element of the stream by simply skipping all the elements before it

public static String FindLasstEntryWithSkipFunctionMethod() {
        final long count = linkedmap.entrySet().stream().count();
        return linkedmap.entrySet().stream().skip(count - 1).findFirst().get().getValue();

Iterable Alternative

Iterables.getLast from Google Guava. It has some optimization for Lists and SortedSets too

public static String FindLasstEntryWithGuavaIterable() {
        return Iterables.getLast(linkedmap.entrySet()).getValue();

Here is the full source code

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class PerformanceTest {

    private static long startTime;
    private static long endTime;
    private static LinkedHashMap<Integer, String> linkedmap;

    public static void main(String[] args) {
        linkedmap = new LinkedHashMap<Integer, String>();

        linkedmap.put(12, "Chaitanya");
        linkedmap.put(2, "Rahul");
        linkedmap.put(7, "Singh");
        linkedmap.put(49, "Ajeet");
        linkedmap.put(76, "Anuj");

        //call a useless action  so that the caching occurs before the jobs starts.
        linkedmap.entrySet().forEach(x -> {});

        startTime = System.nanoTime();
        endTime = System.nanoTime();
        System.out.println("FindLasstEntryWithArrayListMethod : " + "took " + new BigDecimal((endTime - startTime) / 1000000.000).setScale(3, RoundingMode.CEILING) + " milliseconds");

         startTime = System.nanoTime();
        endTime = System.nanoTime();
        System.out.println("FindLasstEntryWithArrayMethod : " + "took " + new BigDecimal((endTime - startTime) / 1000000.000).setScale(3, RoundingMode.CEILING) + " milliseconds");

        startTime = System.nanoTime();
        endTime = System.nanoTime();

        System.out.println("FindLasstEntryWithReduceMethod : " + "took " + new BigDecimal((endTime - startTime) / 1000000.000).setScale(3, RoundingMode.CEILING) + " milliseconds");

        startTime = System.nanoTime();
        endTime = System.nanoTime();

        System.out.println("FindLasstEntryWithSkipFunctionMethod : " + "took " + new BigDecimal((endTime - startTime) / 1000000.000).setScale(3, RoundingMode.CEILING) + " milliseconds");

        startTime = System.currentTimeMillis();
        endTime = System.currentTimeMillis();
        System.out.println("FindLasstEntryWithGuavaIterable : " + "took " + (endTime - startTime) + " milliseconds");


    public static String FindLasstEntryWithReduceMethod() {
        return linkedmap.entrySet().stream().reduce((first, second) -> second).orElse(null).getValue();

    public static String FindLasstEntryWithSkipFunctionMethod() {
        final long count = linkedmap.entrySet().stream().count();
        return linkedmap.entrySet().stream().skip(count - 1).findFirst().get().getValue();

    public static String FindLasstEntryWithGuavaIterable() {
        return Iterables.getLast(linkedmap.entrySet()).getValue();

    public static String FindLasstEntryWithArrayListMethod() {
        List<Entry<Integer, String>> entryList = new ArrayList<Map.Entry<Integer, String>>(linkedmap.entrySet());
        return entryList.get(entryList.size() - 1).getValue();

    public static String FindLasstEntryWithArrayMethod() {
        return String.valueOf(linkedmap.entrySet().toArray()[linkedmap.size() - 1]);

Here is the output with performance of each method

FindLasstEntryWithArrayListMethod : took 0.162 milliseconds
FindLasstEntryWithArrayMethod : took 0.025 milliseconds
FindLasstEntryWithReduceMethod : took 2.776 milliseconds
FindLasstEntryWithSkipFunctionMethod : took 3.396 milliseconds
FindLasstEntryWithGuavaIterable : took 11 milliseconds

How to check if a stored procedure exists before creating it

I realize this has already been marked as answered, but we used to do it like this:

IF NOT EXISTS (SELECT * FROM sys.objects WHERE type = 'P' AND OBJECT_ID = OBJECT_ID('dbo.MyProc'))


Just to avoid dropping the procedure.

How to import a class from default package

Create a new package And then move the classes of default package in new package and use those classes

Why do you need to invoke an anonymous function on the same line?

In summary of the previous comments:

function() {

when not assigned to a variable, yields a syntax error. The code is parsed as a function statement (or definition), which renders the closing parentheses syntactically incorrect. Adding parentheses around the function portion tells the interpreter (and programmer) that this is a function expression (or invocation), as in

(function() {

This is a self-invoking function, meaning it is created anonymously and runs immediately because the invocation happens in the same line where it is declared. This self-invoking function is indicated with the familiar syntax to call a no-argument function, plus added parentheses around the name of the function: (myFunction)();.

There is a good SO discussion JavaScript function syntax.

Where is after pip install?

For RPM-based distributions(like Fedora 19), after running the sudo pip install virtualenvwrapper command, you may find the file at:


MySQL Error #1133 - Can't find any matching row in the user table

To expound on Stephane's answer.

I got this error when I tried to grant remote connections privileges of a particular database to a root user on MySQL server by running the command:

USE database_name;

This gave an error:

ERROR 1133 (42000): Can't find any matching row in the user table

Here's how I fixed it:

First, confirm that your MySQL server allows for remote connections. Use your preferred text editor to open the MySQL server configuration file:

sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf

Scroll down to the bind-address line and ensure that is either commented out or replaced with (to allow all remote connections) or replaced with Ip-Addresses that you want remote connections from.

Once you make the necessary changes, save and exit the configuration file. Apply the changes made to the MySQL config file by restarting the MySQL service:

sudo systemctl restart mysql

Next, log into the MySQL server console on the server it was installed:

mysql -u root -p

Enter your mysql user password

Check the hosts that the user you want has access to already. In my case the user is root:

SELECT host FROM mysql.user WHERE user = "root";

This gave me this output:

| host      |
| localhost |

Next, I ran the command below which is similar to the previous one that was throwing errors, but notice that I added a password to it this time:

USE database_name;
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'my-password';

Note: % grants a user remote access from all hosts on a network. You can specify the Ip-Address of the individual hosts that you want to grant the user access from using the command - GRANT ALL PRIVILEGES ON *.* TO 'root'@'Ip-Address' IDENTIFIED BY 'my-password';

Afterwhich I checked the hosts that the user now has access to. In my case the user is root:

SELECT host FROM mysql.user WHERE user = "root";

This gave me this output:

| host      |
| %         |
| localhost |

Finally, you can try connecting to the MySQL server from another server using the command:

mysql -u username -h mysql-server-ip-address -p

Where u represents user, h represents mysql-server-ip-address and p represents password. So in my case it was:

mysql -u root -h -p

Enter your mysql user password

You should get this output depending on your MySQL server version:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.31 MySQL Community Server (GPL)

Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.


Resources: How to Allow Remote Connections to MySQL

That's all.

I hope this helps

how to get the last character of a string?

Use charAt:

The charAt() method returns the character at the specified index in a string.

You can use this method in conjunction with the length property of a string to get the last character in that string.
For example:

const myString = "";_x000D_
const stringLength = myString.length; // this will be 16_x000D_
console.log('lastChar: ', myString.charAt(stringLength - 1)); // this will be the string

Regex for allowing alphanumeric,-,_ and space

var string = 'test- _ 0Test';
string.match(/^[-_ a-zA-Z0-9]+$/)

What does the "undefined reference to varName" in C mean?

You're getting a linker error, so your extern is working (the compiler compiled a.c without a problem), but when it went to link the object files together at the end it couldn't resolve your extern -- void doSomething(int); wasn't actually found anywhere. Did you mess up the extern? Make sure there's actually a doSomething defined in b.c that takes an int and returns void, and make sure you remembered to include b.c in your file list (i.e. you're doing something like gcc a.c b.c, not just gcc a.c)

Close Bootstrap modal on form submit

I am using rails and ajax too and I had the same problem. just run this code


that worked for me but I am trying to also fix it without using jQuery.

Adding a public key to ~/.ssh/authorized_keys does not log me in automatically

Make sure you've copied the whole public key to authorized_keys; the ssh rsa prefix is necessary for the key to work.

Writing/outputting HTML strings unescaped

Supposing your content is inside a string named mystring...

You can use:


Alternatively you can convert your string to HtmlString or any other type that implements IHtmlString in model or directly inline and use regular @:

@{ var myHtmlString = new HtmlString(mystring);}

How can I uninstall Ruby on ubuntu?

This command should do the trick (provided that you installed it using a dpkg-based packet manager):

aptitude purge ruby

What is the HTML5 equivalent to the align attribute in table cells?

According to the HTML5 CR, which requires continued support to “obsolete” features, too, the align=center attribute is rather tricky. Rendering rules for tables say: td elements with that attribute “are expected to center text within themselves, as if they had their 'text-align' property set to 'center' in a presentational hint, and to align descendants to the center.”

And aligning descendants is defined as so that a browser will “align only those descendants that have both their 'margin-left' and 'margin-right' properties computing to a value other than 'auto', that are over-constrained and that have one of those two margins with a used value forced to a greater value, and that do not themselves have an applicable align attribute. When multiple elements are to align a particular descendant, the most deeply nested such element is expected to override the others. Aligned elements are expected to be aligned by having the used values of their left and right margins be set accordingly.”

So it really depends on the content.

Jquery Ajax beforeSend and success,error & complete

Maybe you can try the following :

var i = 0;
function AjaxSendForm(url, placeholder, form, append) {
var data = $(form).serialize();
append = (append === undefined ? false : true); // whatever, it will evaluate to true or false only
    type: 'POST',
    url: url,
    data: data,
    beforeSend: function() {
        // setting a timeout
    success: function(data) {
        if (append) {
        } else {
    error: function(xhr) { // if error occured
        alert("Error occured.please try again");
        $(placeholder).append(xhr.statusText + xhr.responseText);
    complete: function() {
        if (i <= 0) {
    dataType: 'html'

This way, if the beforeSend statement is called before the complete statement i will be greater than 0 so it will not remove the class. Then only the last call will be able to remove it.

I cannot test it, let me know if it works or not.

Get the Id of current table row with Jquery

Create a class in css name it .buttoncontact, add the class attribute to your buttons

function ClickedRow() {
    $(document).on('click', '.buttoncontact', function () {
        var row = $(this).parents('tr').attr('id');
        var rowtext = $(this).closest('tr').text();

jQuery lose focus event

blur event: when the element loses focus.

focusout event: when the element, or any element inside of it, loses focus.

As there is nothing inside the filter element, both blur and focusout will work in this case.

$(function() {
  $('#filter').blur(function() {

jsfiddle with blur:

$(function() {
  $('#filter').focusout(function() {

jsfiddle with focusout:

Uncaught (in promise) TypeError: Failed to fetch and Cors error

you can use solutions without adding "Access-Control-Allow-Origin": "*", if your server is already using Proxy gateway this issue will not happen because the front and backend will be route in the same IP and port in client side but for development, you need one of this three solution if you don't need extra code 1- simulate the real environment by using a proxy server and configure the front and backend in the same port

2- if you using Chrome you can use the extension called Allow-Control-Allow-Origin: * it will help you to avoid this problem

3- you can use the code but some browsers versions may not support that so try to use one of the previous solutions

the best solution is using a proxy like ngnix its easy to configure and it will simulate the real situation of the production deployment

How do you list the primary key of a SQL Server table?

I am telling a simple Technic which I follow

SP_HELP 'table_name'

run this code as query. Mention your table name at place of table_name for which you want to know Primary Key (don't forget the single quotes). The result will show like attached Image. Hope it will help you

enter image description here

Disabling Minimize & Maximize On WinForm?

public Form1()
//this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
this.MaximizeBox = false;
this.MinimizeBox = false;

Fastest way to update 120 Million records

I break the task up into smaller units. Test with different batch size intervals for your table, until you find an interval that performs optimally. Here is a sample that I have used in the past.

declare @counter int 
declare @numOfRecords int
declare @batchsize int

set @numOfRecords = (SELECT COUNT(*) AS NumberOfRecords FROM <TABLE> with(nolock))
set @counter = 0 
set @batchsize = 2500

set rowcount @batchsize
while @counter < (@numOfRecords/@batchsize) +1
set @counter = @counter + 1 
Update table set int_field = -1 where int_field <> -1;
set rowcount 0

How to pass variable from jade template file to a script file?

If you're like me and you use this method of passing variables a lot, here's a write-less-code solution.

In your node.js route, pass the variables in an object called window, like this:

router.get('/', function (req, res, next) {
    res.render('index', {
        window: {
            instance: instance

Then in your pug/jade layout file (just before the block content), you get them out like this:

if window
    each object, key in window
            window.!{key} = !{JSON.stringify(object)};

As my layout.pug file gets loaded with each pug file, I don't need to 'import' my variables over and over.

This way all variables/objects passed to window 'magically' end up in the real window object of your browser where you can use them in Reactjs, Angular, ... or vanilla javascript.

Who is listening on a given TCP port on Mac OS X?

You can also use:

sudo lsof -i -n -P | grep TCP

This works in Mavericks.

How to assign a select result to a variable?

Try This

SELECT @PrimaryContactKey = c.PrimaryCntctKey
FROM tarcustomer c, tarinvoice i
WHERE i.custkey = c.custkey 
    AND i.invckey = @tmp_key

UPDATE tarinvoice SET confirmtocntctkey = @PrimaryContactKey 
WHERE invckey = @tmp_key
FETCH NEXT FROM @get_invckey INTO @tmp_key

You would declare this variable outside of your loop as just a standard TSQL variable.

I should also note that this is how you would do it for any type of select into a variable, not just when dealing with cursors.

Angular JS POST request not sending JSON data

I have tried your example and it works just fine:

var app = 'AirFare';
var d1 = new Date();
var d2 = new Date();

    url: '/api/test',
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    data: {application: app, from: d1, to: d2}


User-Agent:Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.66 Safari/537.36
Request Payload

Are you using the latest version of AngularJS?

Microsoft.ACE.OLEDB.12.0 is not registered

The easiest fix for me was to change SQL Agent job to run in 32-bit runtime. Go to SQL Job > right click properties > step > edit(step) > Execution option tab > Use 32 bit runtime


How to configure Visual Studio to use Beyond Compare

I'm using VS 2017 with projects hosted with Git on hosting (msdn)

The link above worked for me with the "GITHUB FOR WINDOWS" instructions.

The config file was located where it indicated at "c:\users\username\.gitconfig" and I just changed the BC4's to BC3's for my situation and used the appropriate path:

C:/Program Files (x86)/Beyond Compare 3/bcomp.exe

Foreach in a Foreach in MVC View

Assuming your controller's action method is something like this:

public ActionResult AllCategories(int id = 0)
    return View(db.Categories.Include(p => p.Products).ToList());

Modify your models to be something like this:

public class Product
    public int ID { get; set; }
    public int CategoryID { get; set; }
    //new code
    public virtual Category Category { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public string Path { get; set; }

    //remove code below
    //public virtual ICollection<Category> Categories { get; set; }

public class Category
    public int CategoryID { get; set; }
    public string Name { get; set; }
    //new code
    public virtual ICollection<Product> Products{ get; set; }

Then your since now the controller takes in a Category as Model (instead of a Product):

foreach (var category in Model)
            @foreach (var product in Model.Products)
                // cut for brevity, need to add back more code from original

UPDATED: Add ToList() to the controller return statement.

React Native fetch() Network Request Failed

React Native Docs gives the answer for this.

Apple has blocked implicit cleartext HTTP resource loading. So we need to add the following our project's Info.plist (or equivalent) file.


React Native Docs -> Integration With Existing Apps -> Test your integration -> Add App Transport Security exception

Check if the file exists using VBA

Correction to fileExists from @UberNubIsTrue :

Function fileExists(s_directory As String, s_fileName As String) As Boolean

  Dim obj_fso As Object, obj_dir As Object, obj_file As Object
  Dim ret As Boolean
   Set obj_fso = CreateObject("Scripting.FileSystemObject")
   Set obj_dir = obj_fso.GetFolder(s_directory)
   ret = False
   For Each obj_file In obj_dir.Files
     If obj_fso.fileExists(s_directory & "\" & s_fileName) = True Then
        ret = True
        Exit For
      End If

   Set obj_fso = Nothing
   Set obj_dir = Nothing
   fileExists = ret

 End Function

EDIT: shortened version

' Check if a file exists
Function fileExists(s_directory As String, s_fileName As String) As Boolean

    Dim obj_fso As Object

    Set obj_fso = CreateObject("Scripting.FileSystemObject")
    fileExists = obj_fso.fileExists(s_directory & "\" & s_fileName)

End Function

select a value where it doesn't exist in another table

For your first question there are at least three common methods to choose from:

  • NOT IN

The SQL looks like this:

    FROM TableB
    WHERE TableB.ID = TableA.ID


SELECT TableA.* FROM TableA 
ON TableA.ID = TableB.ID

Depending on which database you are using, the performance of each can vary. For SQL Server (not nullable columns):

NOT EXISTS and NOT IN predicates are the best way to search for missing values, as long as both columns in question are NOT NULL.

Python unexpected EOF while parsing

Use raw_input instead of input :)

If you use input, then the data you type is is interpreted as a Python Expression which means that you end up with gawd knows what type of object in your target variable, and a heck of a wide range of exceptions that can be generated. So you should NOT use input unless you're putting something in for temporary testing, to be used only by someone who knows a bit about Python expressions.

raw_input always returns a string because, heck, that's what you always type in ... but then you can easily convert it to the specific type you want, and catch the specific exceptions that may occur. Hopefully with that explanation, it's a no-brainer to know which you should use.


Note: this is only for Python 2. For Python 3, raw_input() has become plain input() and the Python 2 input() has been removed.

Can a relative sitemap url be used in a robots.txt?

Google crawlers are not smart enough, they can't crawl relative URLs, that's why it's always recommended to use absolute URL's for better crawlability and indexability.

Therefore, you can not use this variation

> sitemap: /sitemap.xml

Recommended syntax is



  • Don't forgot to capitalise the first letter in "sitemap"
  • Don't forgot to put space after "Sitemap:"

What's an appropriate HTTP status code to return by a REST API service for a validation failure?

From RFC 4918 (and also documented at

The 422 (Unprocessable Entity) status code means the server understands the content type of the request entity (hence a 415 (Unsupported Media Type) status code is inappropriate), and the syntax of the request entity is correct (thus a 400 (Bad Request) status code is inappropriate) but was unable to process the contained instructions. For example, this error condition may occur if an XML request body contains well-formed (i.e., syntactically correct), but semantically erroneous, XML instructions.

CSS Vertical align does not work with float


The vertical-align CSS property specifies the vertical alignment of an inline, inline-block or table-cell element.

Read this article for Understanding vertical-align

How do I validate a date string format in python?

The Python dateutil library is designed for this (and more). It will automatically convert this to a datetime object for you and raise a ValueError if it can't.

As an example:

>>> from dateutil.parser import parse
>>> parse("2003-09-25")
datetime.datetime(2003, 9, 25, 0, 0)

This raises a ValueError if the date is not formatted correctly:

>>> parse("2003-09-251")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jacinda/envs/dod-backend-dev/lib/python2.7/site-packages/dateutil/", line 720, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "/Users/jacinda/envs/dod-backend-dev/lib/python2.7/site-packages/dateutil/", line 317, in parse
    ret = default.replace(**repl)
ValueError: day is out of range for month

dateutil is also extremely useful if you start needing to parse other formats in the future, as it can handle most known formats intelligently and allows you to modify your specification: dateutil parsing examples.

It also handles timezones if you need that.

Update based on comments: parse also accepts the keyword argument dayfirst which controls whether the day or month is expected to come first if a date is ambiguous. This defaults to False. E.g.

>>> parse('11/12/2001')
>>> datetime.datetime(2001, 11, 12, 0, 0) # Nov 12
>>> parse('11/12/2001', dayfirst=True)
>>> datetime.datetime(2001, 12, 11, 0, 0) # Dec 11

Good tool to visualise database schema?

I'm start to create own Perl script based on SQL::Translator module (GraphViz). Here are first results.

What's the difference between getRequestURI and getPathInfo methods in HttpServletRequest?

Let's break down the full URL that a client would type into their address bar to reach your servlet:

The parts are:

  1. scheme: http
  2. hostname:
  3. port: 80
  4. context path: awesome-application
  5. servlet path: path/to/servlet
  6. path info: path/info
  7. query: a=1&b=2
  8. fragment: boo

The request URI (returned by getRequestURI) corresponds to parts 4, 5 and 6.

(incidentally, even though you're not asking for this, the method getRequestURL would give you parts 1, 2, 3, 4, 5 and 6).


  • part 4 (the context path) is used to select your particular application out of many other applications that may be running in the server
  • part 5 (the servlet path) is used to select a particular servlet out of many other servlets that may be bundled in your application's WAR
  • part 6 (the path info) is interpreted by your servlet's logic (e.g. it may point to some resource controlled by your servlet).
  • part 7 (the query) is also made available to your servlet using getQueryString
  • part 8 (the fragment) is not even sent to the server and is relevant and known only to the client

The following always holds (except for URL encoding differences):

requestURI = contextPath + servletPath + pathInfo

The following example from the Servlet 3.0 specification is very helpful:

Note: image follows, I don't have the time to recreate in HTML:

enter image description here

Android map v2 zoom to show all the markers

Working fine for me.

From this code, I am displaying multiple markers with particular zoom on map screen.

// Declared variables

private LatLngBounds bounds;
private LatLngBounds.Builder builder;

// Method for adding multiple marker points with drawable icon

private void drawMarker(LatLng point, String text) {

        MarkerOptions markerOptions = new MarkerOptions();


// For adding multiple markers visible on map

    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        builder = new LatLngBounds.Builder();
    for (int i = 0; i < locationList.size(); i++) {

        drawMarker(new LatLng(Double.parseDouble(locationList.get(i).getLatitude()), Double.parseDouble(locationList.get(i).getLongitude())), locationList.get(i).getNo());

     bounds =;
     CameraUpdate cu = CameraUpdateFactory.newLatLngBounds(bounds, 0);

How to use ng-repeat for dictionaries in AngularJs?

You can use

<li ng-repeat="(name, age) in items">{{name}}: {{age}}</li>

See ngRepeat documentation. Example:

Another git process seems to be running in this repository

If you are windows user there will be error 'rm' is not recognized as an internal or external command. That's because rm is a Linux command. So in windows, you can use below to remove the index.lock file inside .git folder

del -f .git/index.lock

Console.log not working at all

You may have used the filter function in the console which will hide anything that doesn't match your query. Remove the query and your messages will display.

HTML/CSS Making a textbox with text that is grayed out, and disappears when I click to enter info, how?

This is an elaborate version, to help you understand

function setVolatileBehavior(elem, onColor, offColor, promptText){ //changed spelling of function name to be the same as name used at invocation below
elem.addEventListener("change", function(){
    if (document.activeElement == elem && elem.value==promptText){
        elem.value=''; = onColor;
    else if (elem.value==''){
        elem.value=promptText; = offColor;
elem.addEventListener("blur", function(){
    if (document.activeElement == elem && elem.value==promptText){
        elem.value=''; = onColor;
    else if (elem.value==''){
        elem.value=promptText; = offColor;
elem.addEventListener("focus", function(){
    if (document.activeElement == elem && elem.value==promptText){
        elem.value=''; = onColor;
    else if (elem.value==''){
        elem.value=promptText; = offColor;

Use like this:


How to check the installed version of React-Native

You can run this command in Terminal:

react-native --version

This will give react-native CLI version

Or check in package.json under

"dependencies": {
    "react": "16.11.0",
    "react-native": "0.62.2",

What is the difference between \r and \n?

in C# I found they use \r\n in a string.

How do ports work with IPv6?

I'm pretty certain that ports only have a part in tcp and udp. So it's exactly the same even if you use a new IP protocol

Bootstrap Carousel image doesn't align properly

@Art L. Richards 's solution didn't work out. now in bootstrap.css, original code has become like this.

.carousel .item > img {
  display: block;
  line-height: 1;

@rnaka530 's code would break the fluid feature of bootstrap.

I don't have a good solution but I did fix it. I observed the bootstrap's carousel example very carefully

I find out that img width has to be larger than the grid width. In span9, width is up to 870px, so you have to prepare a image larger than 870px. If you have more container outside the img, as all the container has border or margin something, you can use image with smaller width.

JS how to cache a variable

I have written a generic caching func() which will cache any variable easily and very readable format. Caching function:

function calculateSomethingMaybe(args){
  return args;

function caching(fn){
  const cache = {};
  return function(){
    const string = arguments[0];
      const result = fn.apply(this, arguments);
      cache[string] = result;
      return result;
    return cache[string];

const letsCache = caching(calculateSomethingMaybe);

console.log(letsCache('a book'), letsCache('a pen'), letsCache('a book'));

How do I rename a repository on GitHub?

This solution is for those users who use GitHub desktop.

  1. Rename your repository from setting on

  2. Now from your desktop click on sync.


Where can I find System.Web.Helpers, System.Web.WebPages, and System.Web.Razor?

The issue is a missing or outdated version of MVC. I was running VS 2015Preview and could resolve the issue by installing the latest version of MVC via NuGet.

Just in case anyone is still coming across this one.

How to filter a data frame

Another method utilizing the dplyr package:

df <- mtcars %>%
        filter(mpg > 25)

Without the chain (%>%) operator:

df <- filter(mtcars, mpg > 25)

What are the differences between C, C# and C++ in terms of real-world applications?

From your other posts, I guess you want to learn a new language to get new skills. My advice is that the language is not really important, what is important is the quality of its community (advice, but also existing code you can read and learn from) and the available libraries/frameworks. In this respect, I think the "C family" is not the best choice for you: web libraries and frameworks are few, not portable and not great, and coding style of code you can study varies a lot and may confuse you a lot (although C is my favorite language).

I would advise to just learn C, and try to really understand the concept of pointers, then move to other languages more adapted to the web (Python or JavaScript comes to mind - or even Java). Also, in the C family, Objective-C has the best mix of power and simplicity in my opinion, but is a niche player.

How to append contents of multiple files into one file

Another option is sed:

sed r 1.txt 2.txt 3.txt > merge.txt 


sed h 1.txt 2.txt 3.txt > merge.txt 


sed -n p 1.txt 2.txt 3.txt > merge.txt # -n is mandatory here

Or without redirection ...

sed wmerge.txt 1.txt 2.txt 3.txt

Note that last line write also merge.txt (not wmerge.txt!). You can use w"merge.txt" to avoid confusion with the file name, and -n for silent output.

Of course, you can also shorten the file list with wildcards. For instance, in case of numbered files as in the above examples, you can specify the range with braces in this way:

sed -n w"merge.txt" {1..3}.txt

'NOT LIKE' in an SQL query

You've missed the id out before the NOT; it needs to be specified.

SELECT * FROM transactions WHERE id NOT LIKE '1%' AND id NOT LIKE '2%'

How to force Chrome's script debugger to reload javascript?

While you are developing your script, try disabling the Chrome cache.

When you reload the page, the JavaScript should now get refreshed.

Chrome circa 2011

Open settings Disable the cache

Chrome circa 2018

Open settings Disable the cache

You can also access it on the network tab:

Network tab

How do I change the database name using MySQL?

I agree with above answers and tips but there is a way to change database name with phpmyadmin

Renaming the Database From cPanel, click on phpMyAdmin. (It should open in a new tab.) Click on the database you wish to rename in the left hand column. Click on the Operations tab. Where it says "Rename database to:" enter the new database name. Click the Go button. When it asks you to want to create the new database and drop the old database, click OK to proceed. (This is a good time to make sure you spelled the new name correctly.) Once the operation is complete, click OK when asked if you want to reload the database.

here's the video tutorial:

ObjectiveC Parse Integer from String

Keep in mind that international users may be using a decimal separator other than . in which case values can get mixed up or just become nil when using intValue on a string.

For example, in the UK 1.23 is written 1,23, so the number 1.777 would be input by user as 1,777, which, as .intValue, will be 1777 not 1 (truncated).

I've made a macro that will convert input text to an NSNumber based on a locale argument which can be nil (if nil it uses device current locale).

#define stringToNumber(__string, __nullable_locale) (\
(^NSNumber *(void){\
NSLocale *__locale = __nullable_locale;\
if (!__locale) {\
__locale = [NSLocale currentLocale];\
NSString *__string_copy = [__string stringByReplacingOccurrencesOfString:__locale.groupingSeparator withString:@""];\
__string_copy = [__string_copy stringByReplacingOccurrencesOfString:__locale.decimalSeparator withString:@"."];\
return @([__string_copy doubleValue]);\

How to rebase local branch onto remote master

Note: If you have broad knowledge already about rebase then use below one liner for fast rebase. Solution: Assuming you are on your working branch and you are the only person working on it.

git fetch && git rebase origin/master

Resolve any conflicts, test your code, commit and push new changes to remote branch.

                            ~:   For noobs   :~

The following steps might help anyone who are new to git rebase and wanted to do it without hassle

Step 1: Assuming that there are no commits and changes to be made on YourBranch at this point. We are visiting YourBranch.

git checkout YourBranch
git pull --rebase

What happened? Pulls all changes made by other developers working on your branch and rebases your changes on top of it.

Step 2: Resolve any conflicts that presents.

Step 3:

git checkout master
git pull --rebase

What happened? Pulls all the latest changes from remote master and rebases local master on remote master. I always keep remote master clean and release ready! And, prefer only to work on master or branches locally. I recommend in doing this until you gets a hand on git changes or commits. Note: This step is not needed if you are not maintaining local master, instead you can do a fetch and rebase remote master directly on local branch directly. As I mentioned in single step in the start.

Step 4: Resolve any conflicts that presents.

Step 5:

git checkout YourBranch
git rebase master

What happened? Rebase on master happens

Step 6: Resolve any conflicts, if there are conflicts. Use git rebase --continue to continue rebase after adding the resolved conflicts. At any time you can use git rebase --abort to abort the rebase.

Step 7:

git push --force-with-lease 

What happened? Pushing changes to your remote YourBranch. --force-with-lease will make sure whether there are any other incoming changes for YourBranch from other developers while you rebasing. This is super useful rather than force push. In case any incoming changes then fetch them to update your local YourBranch before pushing changes.

Why do I need to push changes? To rewrite the commit message in remote YourBranch after proper rebase or If there are any conflicts resolved? Then you need to push the changes you resolved in local repo to the remote repo of YourBranch

Yahoooo...! You are succesfully done with rebasing.

You might also be looking into doing:

git checkout master
git merge YourBranch

When and Why? Merge your branch into master if done with changes by you and other co-developers. Which makes YourBranch up-to-date with master when you wanted to work on same branch later.

                            ~:   (?o 3 o)? rebase   :~

Converting byte array to string in javascript

If your array is encoded in UTF-8 and you can't use the TextDecoder API because it is not supported on IE:

  1. You can use the FastestSmallestTextEncoderDecoder polyfill recommended by the Mozilla Developer Network website;
  2. You can use this function also provided at the MDN website:

function utf8ArrayToString(aBytes) {_x000D_
    var sView = "";_x000D_
    for (var nPart, nLen = aBytes.length, nIdx = 0; nIdx < nLen; nIdx++) {_x000D_
        nPart = aBytes[nIdx];_x000D_
        sView += String.fromCharCode(_x000D_
            nPart > 251 && nPart < 254 && nIdx + 5 < nLen ? /* six bytes */_x000D_
                /* (nPart - 252 << 30) may be not so safe in ECMAScript! So...: */_x000D_
                (nPart - 252) * 1073741824 + (aBytes[++nIdx] - 128 << 24) + (aBytes[++nIdx] - 128 << 18) + (aBytes[++nIdx] - 128 << 12) + (aBytes[++nIdx] - 128 << 6) + aBytes[++nIdx] - 128_x000D_
            : nPart > 247 && nPart < 252 && nIdx + 4 < nLen ? /* five bytes */_x000D_
                (nPart - 248 << 24) + (aBytes[++nIdx] - 128 << 18) + (aBytes[++nIdx] - 128 << 12) + (aBytes[++nIdx] - 128 << 6) + aBytes[++nIdx] - 128_x000D_
            : nPart > 239 && nPart < 248 && nIdx + 3 < nLen ? /* four bytes */_x000D_
                (nPart - 240 << 18) + (aBytes[++nIdx] - 128 << 12) + (aBytes[++nIdx] - 128 << 6) + aBytes[++nIdx] - 128_x000D_
            : nPart > 223 && nPart < 240 && nIdx + 2 < nLen ? /* three bytes */_x000D_
                (nPart - 224 << 12) + (aBytes[++nIdx] - 128 << 6) + aBytes[++nIdx] - 128_x000D_
            : nPart > 191 && nPart < 224 && nIdx + 1 < nLen ? /* two bytes */_x000D_
                (nPart - 192 << 6) + aBytes[++nIdx] - 128_x000D_
            : /* nPart < 127 ? */ /* one byte */_x000D_
    return sView;_x000D_
let str = utf8ArrayToString([50,72,226,130,130,32,43,32,79,226,130,130,32,226,135,140,32,50,72,226,130,130,79]);_x000D_
// Must show 2H2 + O2 ? 2H2O_x000D_

How do I look inside a Python object?

Try using:

  • where object is the variable name of the object you are trying to inspect.

This prints out a nicely formatted and tabbed output showing all the hierarchy of keys and values in the object.

NOTE: This works in python3. Not sure if it works in earlier versions

UPDATE: This doesn't work on all types of objects. If you encounter one of those types (like a Request object), use one of the following instead:

  • dir(object())


import pprint then: pprint.pprint(object.__dict__)

Creating a PHP header/footer

Besides just using include() or include_once() to include the header and footer, one thing I have found useful is being able to have a custom page title or custom head tags to be included for each page, yet still have the header in a partial include. I usually accomplish this as follows:

In the site pages:


$PageTitle="New Page Title";

function customPageHeader(){?>
  <!--Arbitrary HTML Tags-->
<?php }


//body contents go here


And, in the header.php file:

<!doctype html>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <title><?= isset($PageTitle) ? $PageTitle : "Default Title"?></title>
    <!-- Additional tags here -->
    <?php if (function_exists('customPageHeader')){

Maybe a bit beyond the scope of your original question, but it is useful to allow a bit more flexibility with the include.

JQuery: if div is visible

You can use .is(':visible')

Selects all elements that are visible.

For example:


Also, you can get the div which is visible by:


Live example:

#selectDiv {_x000D_
  display: none;  _x000D_
<script src=""></script>_x000D_
<div id="selectDiv"></div>_x000D_
<div id="visibleDiv"></div>

SQL Query with Join, Count and Where

SELECT COUNT(*), table1.category_id, table2.category_name 
FROM table1 
INNER JOIN table2 ON table1.category_id=table2.category_id 
WHERE table1.colour <> 'red'
GROUP BY table1.category_id, table2.category_name 

Darken background image on hover

I was able to achieve this more easily than the above answers and in a single line of code by using the new Filter CSS option.

It's compatibility in modern browsers is pretty good - 95% at time of writing, though less than the other answers.

  filter: brightness(50%);_x000D_
<img src=''>

Parcelable encountered IOException writing serializable object getactivity()

If you can't make DNode serializable a good solution would be to add "transient" to the variable.


public static transient DNode dNode = null;

This will ignore the variable when using Intent.putExtra(...).

Remove gutter space for a specific div only

For Bootstrap 3.0 or higher, see this answer

We're only looking at class .span1 here (one column on a 12 wide grid), but you can achieve what you want by removing the left margin from:

.row-fluid [class*="span"] { margin:0 } // line 571 of bootstrap responsive

Then changing .row-fluid .span1's width to equal to 100% divided by 12 columns (8.3333%).

.row-fluid .span1 { width: 8.33334% } // line 632 of bootstrap responsive

You may want to do this by adding an additional class that would allow you to leave the base grid system intact:

.row-fluid [class*="NoGutter"] { margin-left:0 }
.row-fluid .span1NoGutter { width: 8.33334% }

<div class="row-fluid show-grid">
    <div class="span1NoGutter">1</div>

You could repeat this pattern for all other columns, as well:

.row-fluid .span2NoGutter { width:16.66667%; margin-left:0 } // 100% / 6 col
.row-fluid .span4NoGutter { width:25%; margin-left:0 } // 100% / 4 col
.row-fluid .span3NoGutter { width:33.33333%; margin-left:0 } // 100% / 3 col
.row-fluid .span4NoGutter { width:25% }
.row-fluid [class*="NoGutter"] { margin-left:0 }

* EDIT (insisting on using the default grid)
If the default grid system is a requirement, it defaults to a width of 940px (the .container and .span12 classes, that is); thus, in simplest terms, you'd want to divide 940 by 12. That equates to 12 containers 78.33333px wide.

So line 339 of bootstrap.css could be edited like so:

.span1 { width:78.33333px; margin-left:0 }
.span1 { width:8.33334%; margin-left:0 }
// this should render at 78.333396px (78.333396 x 12 = 940.000752)

How to split a string content into an array of strings in PowerShell?

As of PowerShell 2, simple:

$recipients = $addresses -split "; "

Note that the right hand side is actually a case-insensitive regular expression, not a simple match. Use csplit to force case-sensitivity. See about_Split for more details.

Is there a label/goto in Python?

No, Python does not support labels and goto, if that is what you're after. It's a (highly) structured programming language.

mongodb how to get max value from collections

The performance of the suggested answer is fine. According to the MongoDB documentation:

When a $sort immediately precedes a $limit, the optimizer can coalesce the $limit into the $sort. This allows the sort operation to only maintain the top n results as it progresses, where n is the specified limit, and MongoDB only needs to store n items in memory.

Changed in version 4.0.

So in the case of


we get only the highest element WITHOUT sorting the collection because of the mentioned optimization.

How to remove commits from a pull request

This is what helped me:

  1. Create a new branch with the existing one. Let's call the existing one branch_old and new as branch_new.

  2. Reset branch_new to a stable state, when you did not have any problem commit at all. For example, to put it at your local master's level do the following:

    git reset —hard master git push —force origin

  3. cherry-pick the commits from branch_old into branch_new

  4. git push

[Ljava.lang.Object; cannot be cast to

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to

Problem is

(List<SwitcherServiceSource>) LoadSource.list();

This will return a List of Object arrays (Object[]) with scalar values for each column in the SwitcherServiceSource table. Hibernate will use ResultSetMetadata to deduce the actual order and types of the returned scalar values.


List<Object> result = (List<Object>) LoadSource.list(); 
Iterator itr = result.iterator();
   Object[] obj = (Object[]);
   //now you have one array of Object for each row
   String client = String.valueOf(obj[0]); // don't know the type of column CLIENT assuming String 
   Integer service = Integer.parseInt(String.valueOf(obj[1])); //SERVICE assumed as int
   //same way for all obj[2], obj[3], obj[4]

Related link

Package php5 have no installation candidate (Ubuntu 16.04)

Currently, I am using Ubuntu 16.04 LTS. Me too was facing same problem while Fetching the Postgress Database values using Php so i resolved it by using the below commands.

Mine PHP version is 7.0, so i tried the below command.

apt-get install php-pgsql

Remember to restart Apache.

/etc/init.d/apache2 restart

Escape double quotes in a string


Either use verbatim string literals as you have, or escape the " using backslash.

string test = "He said to me, \"Hello World\" . How are you?";

The string has not changed in either case - there is a single escaped " in it. This is just a way to tell C# that the character is part of the string and not a string terminator.

The controller for path was not found or does not implement IController

In my case, the same error was not related to Area but thought to post the error caused in my case, which may be helpful for the people who come to this thread by searching "The controller for path was not found or does not implement IController"

The error was caused because of wrong entry in _Layout.cshtml file.


The bundle with that name was removed in BundleConfig.cs but forgot to remove it in _Layout.cshtml

It was silly, but we programmers always do lot of silly mistakes :)

SQLite string contains other string query

Using LIKE:

 WHERE column LIKE '%cats%'  --case-insensitive

ORDER BY the IN value list

I agree with all other posters that say "don't do that" or "SQL isn't good at that". If you want to sort by some facet of comments then add another integer column to one of your tables to hold your sort criteria and sort by that value. eg "ORDER BY comments.sort DESC " If you want to sort these in a different order every time then... SQL won't be for you in this case.

Simple parse JSON from URL on Android and display in listview

import java.util.HashMap;

public class GetJsonFromUrl {
    String url = null;

    public GetJsonFromUrl(String url) {
        this.url = url;

    public String GetJsonData() {
        try {
            URL Url = new URL(url);
            HttpURLConnection connection = (HttpURLConnection) Url.openConnection();
            InputStream is = connection.getInputStream();
            BufferedReader br = new BufferedReader(new InputStreamReader(is));
            StringBuilder sb = new StringBuilder();
            String line;
            while ((line = br.readLine()) != null) {
            line = sb.toString();
            sb.delete(0, sb.length());
            return line;
        } catch (Exception e) {
            return null;

and this class use for post data

import android.util.Log;

import java.util.HashMap;
import java.util.Map;


 * Created by user on 11/2/16.
public class sendDataToServer {
   public String postdata(String requestURL,HashMap<String,String> postDataParams){
        try {
            String response = "";
            URL url = new URL(requestURL);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            OutputStream os = conn.getOutputStream();
            BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(os, "UTF-8"));

            String line;
            BufferedReader br=new BufferedReader(new InputStreamReader(conn.getInputStream()));
            while ((line=br.readLine()) != null) {
            Log.d("test", response);
            return response;
        }catch (Exception e){
            return e.toString();

    public String postjson(String url,String json){
        try {

            URL obj = new URL(url);
            HttpURLConnection con= (HttpURLConnection) obj.openConnection();

            //add reuqest header
            con.setRequestProperty("Accept", "application/json");
            String urlParameters = ""+json;

            // Send post request
            con.setRequestProperty("Content-Type", "application/json");
            OutputStreamWriter wr = new OutputStreamWriter(con.getOutputStream());

            int responseCode = con.getResponseCode();
            System.out.println("\nSending 'POST' request to URL : " + url);
            System.out.println("Post parameters : " + urlParameters);
            System.out.println("Response Code : " + responseCode);

            BufferedReader in = new BufferedReader(
                    new InputStreamReader(con.getInputStream()));
            String inputLine;
            StringBuffer response = new StringBuffer();

            while ((inputLine = in.readLine()) != null) {

            //print result
            return response.toString();
        }catch(Exception e){

            return e.toString();

    private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
        StringBuilder result = new StringBuilder();
        boolean first = true;
        for(Map.Entry<String, String> entry : params.entrySet()){
            if (first)
                first = false;

            result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
            result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
        return result.toString();

   /* public String postdata(String url) {

HTML anchor link - href and onclick both?

If the link should only change the location if the function run is successful, then do onclick="return runMyFunction();" and in the function you would return true or false.

If you just want to run the function, and then let the anchor tag do its job, simply remove the return false statement.

As a side note, you should probably use an event handler instead, as inline JS isn't a very optimal way of doing things.

In jQuery, what's the best way of formatting a number to 2 decimal places?

Maybe something like this, where you could select more than one element if you'd like?


How to initialize a static array?

If you are creating an array then there is no difference, however, the following is neater:

String[] suit = {

But, if you want to pass an array into a method you have to call it like this:

myMethod(new String[] {"spades", "hearts"});

myMethod({"spades", "hearts"}); //won't compile!

Javascript "Uncaught TypeError: object is not a function" associativity question

JavaScript does require semicolons, it's just that the interpreter will insert them for you on line breaks where possible*.

Unfortunately, the code

var a = new B(args)(stuff)()

does not result in a syntax error, so no ; will be inserted. (An example which can run is

var answer = new Function("x", "return x")(function(){return 42;})();

To avoid surprises like this, train yourself to always end a statement with ;.

* This is just a rule of thumb and not always true. The insertion rule is much more complicated. This blog page about semicolon insertion has more detail.