Programs & Examples On #Feature branch

Rebasing remote branches in Git

Nice that you brought this subject up.

This is an important thing/concept in git that a lof of git users would benefit from knowing. git rebase is a very powerful tool and enables you to squash commits together, remove commits etc. But as with any powerful tool, you basically need to know what you're doing or something might go really wrong.

When you are working locally and messing around with your local branches, you can do whatever you like as long as you haven't pushed the changes to the central repository. This means you can rewrite your own history, but not others history. By only messing around with your local stuff, nothing will have any impact on other repositories.

This is why it's important to remember that once you have pushed commits, you should not rebase them later on. The reason why this is important, is that other people might pull in your commits and base their work on your contributions to the code base, and if you later on decide to move that content from one place to another (rebase it) and push those changes, then other people will get problems and have to rebase their code. Now imagine you have 1000 developers :) It just causes a lot of unnecessary rework.

Rebase feature branch onto another feature branch

Note: if you were on Branch1, you will with Git 2.0 (Q2 2014) be able to type:

git checkout Branch2
git rebase -

See commit 4f40740 by Brian Gesiak modocache:

rebase: allow "-" short-hand for the previous branch

Teach rebase the same shorthand as checkout and merge to name the branch to rebase the current branch on; that is, that "-" means "the branch we were previously on".

Git merge master into feature branch

Complementing the existing answers, as these commands are recurrent we can do it in a row. Given we are in the feature branch:

git checkout master && git pull && git checkout - && git merge -

Or add them in an alias:

alias merge_with_master="git checkout master && git pull && git checkout - && git merge -"

How can I delete all Git branches which have been merged?

To avoid accidentally running the command from any other branch than master I use the following bash script. Otherwise, running git branch --merged | grep -v "\*" | xargs -n 1 git branch -d from a branch that has been merged of off master could delete the master branch.


branch_name="$(git symbolic-ref HEAD 2>/dev/null)" ||
branch_name="(unnamed branch)"     # detached HEAD

if [[ $branch_name == 'master' ]]; then
   read -r -p "Are you sure? [y/N] " response
   if [[ $response =~ ^([yY][eE][sS]|[yY])$ ]]; then
       git branch --merged | grep -v "\*" | xargs -n 1 git branch -d
   echo "Refusing to delete branches that are not merged into '$branch_name'. Checkout master first."

How to delete last character in a string in C#?

string source;
// source gets initialized
string dest;
if (source.Length > 0)
    dest = source.Substring(0, source.Length - 1);

How do I install the babel-polyfill library?

For Babel version 7, if your are using @babel/preset-env, to include polyfill all you have to do is add a flag 'useBuiltIns' with the value of 'usage' in your babel configuration. There is no need to require or import polyfill at the entry point of your App.

With this flag specified, babel@7 will optimize and only include the polyfills you needs.

To use this flag, after installation:

npm install --save-dev  @babel/core @babel/cli @babel/preset-env
npm install --save @babel/polyfill

Simply add the flag:

useBuiltIns: "usage" 

to your babel configuration file called "babel.config.js" (also new to Babel@7), under the "@babel/env" section:

// file: babel.config.js

module.exports = () => {
   const presets = [
             targets: { /* your targeted browser */ },
             useBuiltIns: "usage"  // <-----------------*** add this

   return { presets };


Update Aug 2019:

With the release of Babel 7.4.0 (March 19, 2019) @babel/polyfill is deprecated. Instead of installing @babe/polyfill, you will install core-js:

npm install --save core-js@3

A new entry corejs is added to your babel.config.js

// file: babel.config.js

module.exports = () => {
   const presets = [
             targets: { /* your targeted browser */ },
             useBuiltIns: "usage",
             corejs: 3  // <----- specify version of corejs used

   return { presets };

see example:


How to drop rows of Pandas DataFrame whose value in a certain column is NaN

How to drop rows of Pandas DataFrame whose value in a certain column is NaN

This is an old question which has been beaten to death but I do believe there is some more useful information to be surfaced on this thread. Read on if you're looking for the answer to any of the following questions:

  • Can I drop rows if any of its values have NaNs? What about if all of them are NaN?
  • Can I only look at NaNs in specific columns when dropping rows?
  • Can I drop rows with a specific count of NaN values?
  • How do I drop columns instead of rows?
  • I tried all of the options above but my DataFrame just won't update!

DataFrame.dropna: Usage, and Examples

It's already been said that df.dropna is the canonical method to drop NaNs from DataFrames, but there's nothing like a few visual cues to help along the way.

# Setup
df = pd.DataFrame({
    'A': [np.nan, 2, 3, 4],  
    'B': [np.nan, np.nan, 2, 3], 
    'C': [np.nan]*3 + [3]}) 

     A    B    C
0  NaN  NaN  NaN
1  2.0  NaN  NaN
2  3.0  2.0  NaN
3  4.0  3.0  3.0

Below is a detail of the most important arguments and how they work, arranged in an FAQ format.

Can I drop rows if any of its values have NaNs? What about if all of them are NaN?

This is where the how=... argument comes in handy. It can be one of

  • 'any' (default) - drops rows if at least one column has NaN
  • 'all' - drops rows only if all of its columns have NaNs

<!_ ->

# Removes all but the last row since there are no NaNs 

     A    B    C
3  4.0  3.0  3.0

# Removes the first row only

     A    B    C
1  2.0  NaN  NaN
2  3.0  2.0  NaN
3  4.0  3.0  3.0

If you just want to see which rows are null (IOW, if you want a boolean mask of rows), use isna:


       A      B      C
0   True   True   True
1  False   True   True
2  False  False   True
3  False  False  False


0     True
1     True
2     True
3    False
dtype: bool

To get the inversion of this result, use notna instead.

Can I only look at NaNs in specific columns when dropping rows?

This is a use case for the subset=[...] argument.

Specify a list of columns (or indexes with axis=1) to tells pandas you only want to look at these columns (or rows with axis=1) when dropping rows (or columns with axis=1.

# Drop all rows with NaNs in A

     A    B    C
1  2.0  NaN  NaN
2  3.0  2.0  NaN
3  4.0  3.0  3.0

# Drop all rows with NaNs in A OR B
df.dropna(subset=['A', 'B'])

     A    B    C
2  3.0  2.0  NaN
3  4.0  3.0  3.0

Can I drop rows with a specific count of NaN values?

This is a use case for the thresh=... argument. Specify the minimum number of NON-NULL values as an integer.


     A    B    C
1  2.0  NaN  NaN
2  3.0  2.0  NaN
3  4.0  3.0  3.0


     A    B    C
2  3.0  2.0  NaN
3  4.0  3.0  3.0


     A    B    C
3  4.0  3.0  3.0

The thing to note here is you need to specify how many NON-NULL values you want to keep, rather than how many NULL values you want to drop. This is a pain point for new users.

Luckily the fix is easy: if you have a count of NULL values, simply subtract it from the column size to get the correct thresh argument for the function.

required_min_null_values_to_drop = 2 # drop rows with at least 2 NaN
df.dropna(thresh=df.shape[1] - required_min_null_values_to_drop + 1)

     A    B    C
2  3.0  2.0  NaN
3  4.0  3.0  3.0

How do I drop columns instead of rows?

Use the axis=... argument, it can be axis=0 or axis=1.

Tells the function whether you want to drop rows (axis=0) or drop columns (axis=1).


     A    B    C
3  4.0  3.0  3.0

# All columns have rows, so the result is empty.

Empty DataFrame
Columns: []
Index: [0, 1, 2, 3]

# Here's a different example requiring the column to have all NaN rows
# to be dropped. In this case no columns satisfy the condition.
df.dropna(axis=1, how='all')

     A    B    C
0  NaN  NaN  NaN
1  2.0  NaN  NaN
2  3.0  2.0  NaN
3  4.0  3.0  3.0

# Here's a different example requiring a column to have at least 2 NON-NULL
# values. Column C has less than 2 NON-NULL values, so it should be dropped.
df.dropna(axis=1, thresh=2)

     A    B
0  NaN  NaN
1  2.0  NaN
2  3.0  2.0
3  4.0  3.0

I tried all of the options above but my DataFrame just won't update!

dropna, like most other functions in the pandas API returns a new DataFrame (a copy of the original with changes) as the result, so you should assign it back if you want to see changes.

df.dropna(...) # wrong
df.dropna(..., inplace=True) # right, but not recommended
df = df.dropna(...) # right


    self, axis=0, how='any', thresh=None, subset=None, inplace=False)

enter image description here

Swift 2: Call can throw, but it is not marked with 'try' and the error is not handled

You have to catch the error just as you're already doing for your save() call and since you're handling multiple errors here, you can try multiple calls sequentially in a single do-catch block, like so:

func deleteAccountDetail() {
    let entityDescription = NSEntityDescription.entityForName("AccountDetail", inManagedObjectContext: Context!)
    let request = NSFetchRequest()
    request.entity = entityDescription

    do {
        let fetchedEntities = try self.Context!.executeFetchRequest(request) as! [AccountDetail]

        for entity in fetchedEntities {

        try self.Context!.save()
    } catch {

Or as @bames53 pointed out in the comments below, it is often better practice not to catch the error where it was thrown. You can mark the method as throws then try to call the method. For example:

func deleteAccountDetail() throws {
    let entityDescription = NSEntityDescription.entityForName("AccountDetail", inManagedObjectContext: Context!)
    let request = NSFetchRequest()

    request.entity = entityDescription

    let fetchedEntities = try Context.executeFetchRequest(request) as! [AccountDetail]

    for entity in fetchedEntities {

    try self.Context!.save()

Get element from within an iFrame

Do not forget to access iframe after it is loaded. Old but reliable way without jQuery:

<iframe src="" id="iframe" onload="access()"></iframe>

function access() {
   var iframe = document.getElementById("iframe");
   var innerDoc = iframe.contentDocument || iframe.contentWindow.document;
</script> Software caused connection abort: recv failed

I too had this problem. My solution was:

sc.setSoLinger(true, 10);

COPY FROM A WEBSITE -->By using the setSoLinger() method, you can explicitly set a delay before a reset is sent, giving more time for data to be read or send.

Maybe it is not the answer to everybody but to some people.

How to run a single RSpec test?

For single example of spec file you need to add line number at the last , For Example

rspec spec/controllers/api/v1/card_list_controller_spec.rb:35

For single file you can specify your file path, For Example

rspec spec/controllers/api/v1/card_list_controller_spec.rb

For Whole Rspec Example in spec folder, you can try with this command

bundle exec rspec spec

How can I find the length of a number?

A way for integers without banal converting to string:

var num = 9999999999; // your number
var length = 1;
while (num >= 10) {
   num /= 10;

Regular expression: zero or more occurrences of optional character /


If your delimiters are slash-based, escape it:


* means "0 or more of the previous repeatable pattern", which can be a single character, a character class or a group.

How to convert a list into data table

you can use this extension method and call it like this.

DataTable dt =   YourList.ToDataTable();

public static DataTable ToDataTable<T>(this List<T> iList)
            DataTable dataTable = new DataTable();
            PropertyDescriptorCollection propertyDescriptorCollection =
            for (int i = 0; i < propertyDescriptorCollection.Count; i++)
                PropertyDescriptor propertyDescriptor = propertyDescriptorCollection[i];
                Type type = propertyDescriptor.PropertyType;

                if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
                    type = Nullable.GetUnderlyingType(type);

                dataTable.Columns.Add(propertyDescriptor.Name, type);
            object[] values = new object[propertyDescriptorCollection.Count];
            foreach (T iListItem in iList)
                for (int i = 0; i < values.Length; i++)
                    values[i] = propertyDescriptorCollection[i].GetValue(iListItem);
            return dataTable;

VLook-Up Match first 3 characters of one column with another column


Use CSS to automatically add 'required field' asterisk to form inputs

Use jQuery and CSS

jQuery(document).ready(function() {_x000D_
 jQuery("[required]").after("<span class='required'>*</span>");_x000D_
.required {_x000D_
    position: absolute;_x000D_
    margin-left: -10px;_x000D_
    color: #FB0000;_x000D_
    font-size: 15px;_x000D_
<script src=""></script>_x000D_
<input type="text" value="xxx" required>

TypeError: int() argument must be a string, a bytes-like object or a number, not 'list'

What the error is telling, is that you can't convert an entire list into an integer. You could get an index from the list and convert that into an integer:

x = ["0", "1", "2"] 
y = int(x[0]) #accessing the zeroth element

If you're trying to convert a whole list into an integer, you are going to have to convert the list into a string first:

x = ["0", "1", "2"]
y = ''.join(x) # converting list into string
z = int(y)

If your list elements are not strings, you'll have to convert them to strings before using str.join:

x = [0, 1, 2]
y = ''.join(map(str, x))
z = int(y)

Also, as stated above, make sure that you're not returning a nested list.

What to do with branch after merge

I prefer RENAME rather than DELETE

All my branches are named in the form of

  • Fix/fix-<somedescription> or
  • Ftr/ftr-<somedescription> or
  • etc.

Using Tower as my git front end, it neatly organizes all the Ftr/, Fix/, Test/ etc. into folders.
Once I am done with a branch, I rename them to Done/...-<description>.

That way they are still there (which can be handy to provide history) and I can always go back knowing what it was (feature, fix, test, etc.)

What is an efficient way to implement a singleton pattern in Java?

Sometimes a simple "static Foo foo = new Foo();" is not enough. Just think of some basic data insertion you want to do.

On the other hand you would have to synchronize any method that instantiates the singleton variable as such. Synchronisation is not bad as such, but it can lead to performance issues or locking (in very very rare situations using this example. The solution is

public class Singleton {

    private static Singleton instance = null;

    static {
          instance = new Singleton();
          // do some of your instantiation stuff here

    private Singleton() {
          if(instance!=null) {
                  throw new ErrorYouWant("Singleton double-instantiation, should never happen!");

    public static getSingleton() {
          return instance;


Now what happens? The class is loaded via the class loader. Directly after the class was interpreted from a byte Array, the VM executes the static { } - block. that's the whole secret: The static-block is only called once, the time the given class (name) of the given package is loaded by this one class loader.

Playing .mp3 and .wav in Java?

I wrote a pure java mp3 player: mp3transform.

Simple way to check if a string contains another string in C?

if (strstr(request, "favicon") != NULL) {
    // contains

How to count the number of lines of a string in javascript

Using a regular expression you can count the number of lines as


Alternately you can try split method as below.

var lines = $("#ptest").val().split("\n");  

working solution:

How do I toggle an ng-show in AngularJS based on a boolean?

Basically I solved it by NOT-ing the isReplyFormOpen value whenever it is clicked:

<a ng-click="isReplyFormOpen = !isReplyFormOpen">Reply</a>

<div ng-init="isReplyFormOpen = false" ng-show="isReplyFormOpen" id="replyForm">
    <!-- Form -->

How to cut an entire line in vim and paste it?

  1. press 'V' in normal mode to select the entire line
  2. then press 'y' to copy it
  3. go to the place you want to paste it and press 'p' to paste after cursor or 'P' to paste before it.

Pdf.js: rendering a pdf file using a base64 file source instead of url

Used the Accepted Answer to do a check for IE and convert the dataURI to UInt8Array; an accepted form by PDFJS

        Ext.isIE ? pdfAsDataUri = me.convertDataURIToBinary(pdfAsDataUri): '';_x000D_
        convertDataURIToBinary: function(dataURI) {_x000D_
          var BASE64_MARKER = ';base64,',_x000D_
            base64Index = dataURI.indexOf(BASE64_MARKER) + BASE64_MARKER.length,_x000D_
            base64 = dataURI.substring(base64Index),_x000D_
            raw = window.atob(base64),_x000D_
            rawLength = raw.length,_x000D_
            array = new Uint8Array(new ArrayBuffer(rawLength));_x000D_
          for (var i = 0; i < rawLength; i++) {_x000D_
            array[i] = raw.charCodeAt(i);_x000D_
          return array;_x000D_

Core dump file analysis

Steps to debug coredump using GDB:

Some generic help:

gdb start GDB, with no debugging les

gdb program begin debugging program

gdb program core debug coredump core produced by program

gdb --help describe command line options

  1. First of all, find the directory where the corefile is generated.

  2. Then use ls -ltr command in the directory to find the latest generated corefile.

  3. To load the corefile use

    gdb binary path of corefile

    This will load the corefile.

  4. Then you can get the information using the bt command.

    For a detailed backtrace use bt full.

  5. To print the variables, use print variable-name or p variable-name

  6. To get any help on GDB, use the help option or use apropos search-topic

  7. Use frame frame-number to go to the desired frame number.

  8. Use up n and down n commands to select frame n frames up and select frame n frames down respectively.

  9. To stop GDB, use quit or q.

Word count from a txt file program

for word in
    if word not in wordcount:
        wordcount[word] = 1
        wordcount[word] += 1
for k,v in wordcount.items():
    print k, v

Microsoft.Office.Core Reference Missing

I faced the same problem when i tried to open my old c# project into visual studio 2017 version. This problem arises typically when you try to open a project that you made with previous version of VS and open it with latest version. what i did is,i opened my project and delete the reference from my project,then added Microsoft outlook 12.0 object library and Microsoft office 12.0 object libraryMicrosoft outlook 12.0 object library

javascript functions to show and hide divs

Rename the closing function as 'hide', for example and it will work.

function hide() {
    if(document.getElementById('benefits').style.display=='block') {

Making HTML page zoom by default

A better solution is not to make your page dependable on zoom settings. If you set limits like the one you are proposing, you are limiting accessibility. If someone cannot read your text well, they just won't be able to change that. I would use proper CSS to make it look nice in any zoom.

If your really insist, take a look at this question on how to detect zoom level using JavaScript (nightmare!): How to detect page zoom level in all modern browsers?

Function of Project > Clean in Eclipse

I also faced the same issue with Eclipse when I ran the clean build with Maven, but there is a simple solution for this issue. We just need to run Maven update and then build or direct run the application. I hope it will solve the problem.

How to set Java environment path in Ubuntu

All you have to do now is to set the “JAVA_HOME” and “PATH” environment variables and then you are done. Enter the following commands to set your environment variables. Make sure that your environment variables point to a valid installation of JDK on your machine. For Ubuntu 18.04, the path is /usr/lib/jvm/java-8-openjdk-amd64/

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64

To check whether your JAVA_HOME path has been successfully saved, enter the following command to check.


C# Convert List<string> to Dictionary<string, string>

Use this:

var dict = list.ToDictionary(x => x);

See MSDN for more info.

As Pranay points out in the comments, this will fail if an item exists in the list multiple times.
Depending on your specific requirements, you can either use var dict = list.Distinct().ToDictionary(x => x); to get a dictionary of distinct items or you can use ToLookup instead:

var dict = list.ToLookup(x => x);

This will return an ILookup<string, string> which is essentially the same as IDictionary<string, IEnumerable<string>>, so you will have a list of distinct keys with each string instance under it.

How to re-index all subarray elements of a multidimensional array?

$result = ['5' => 'cherry', '7' => 'apple'];
array_multisort($result, SORT_ASC);

Array ( [0] => apple [1] => cherry )

array_multisort($result, SORT_DESC);

Array ( [0] => cherry [1] => apple )

Can I do Android Programming in C++, C?

You can use the Android NDK, but answers should note that the Android NDK app is not free to use and there's no clear open source route to programming Android on Android in an increasingly Android-driven market that began as open source, with Android developer support or the extensiveness of the NDK app, meaning you're looking at abandoning Android as any kind of first steps programming platform without payments.

Note: I consider subscription requests as payments under duress and this is a freemium context which continues to go undefeated by the open source community.

No numeric types to aggregate - change in groupby() behaviour?

I got this error generating a data frame consisting of timestamps and data:

df = pd.DataFrame({'data':value}, index=pd.DatetimeIndex(timestamp))

Adding the suggested solution works for me:

df = pd.DataFrame({'data':value}, index=pd.DatetimeIndex(timestamp), dtype=float))

Thanks Chang She!


2005-01-01 00:10:00  7.53
2005-01-01 00:20:00  7.54
2005-01-01 00:30:00  7.62
2005-01-01 00:40:00  7.68
2005-01-01 00:50:00  7.81
2005-01-01 01:00:00  7.95
2005-01-01 01:10:00  7.96
2005-01-01 01:20:00  7.95
2005-01-01 01:30:00  7.98
2005-01-01 01:40:00  8.06
2005-01-01 01:50:00  8.04
2005-01-01 02:00:00  8.06
2005-01-01 02:10:00  8.12
2005-01-01 02:20:00  8.12
2005-01-01 02:30:00  8.25
2005-01-01 02:40:00  8.27
2005-01-01 02:50:00  8.17
2005-01-01 03:00:00  8.21
2005-01-01 03:10:00  8.29
2005-01-01 03:20:00  8.31
2005-01-01 03:30:00  8.25
2005-01-01 03:40:00  8.19
2005-01-01 03:50:00  8.17
2005-01-01 04:00:00  8.18
2005-01-01 00:00:00  7.636000
2005-01-01 01:00:00  7.990000
2005-01-01 02:00:00  8.165000
2005-01-01 03:00:00  8.236667
2005-01-01 04:00:00  8.180000

Google Maps V3 - How to calculate the zoom level for a given bounds

Work example to find average default center with react-google-maps on ES6:

const bounds = new google.maps.LatLngBounds(); => bounds.extend(new google.maps.LatLng(latLng)));
const defaultCenter = bounds.getCenter();
 defaultZoom={paths.length ? 12 : 4}
 <Marker position={{ lat, lng }} />

How to resolve Nodejs: Error: ENOENT: no such file or directory

In my case, the issue occurred after I switched from a git branch to another, references to some old files remained in the scripts inside "node_modules/.cache" directory.
Deleting "node_modules", "build" directories and "package-lock.json" file then issuing "npm install" command has fixed the issue for me

Read url to string in few lines of java code

If your url is of type, then you can just convert it to uri and then to string


Change One Cell's Data in mysql

Try the following:

UPDATE TableName SET ValueName=@parameterName WHERE

How to access a mobile's camera from a web app?

Just to update this, the standard now is:

<input type="file" name="image" accept="image/*" capture="environment">

to access the environment-facing (rear) camera, and

<input type="file" name="image" accept="image/*" capture="user">

for user-facing (front) camera. To access video, substitute "video" for "image" in name.

Tested on iPhone 5c, running iOS 10.3.3, firmware 760, works fine.

Error : No resource found that matches the given name (at 'icon' with value '@drawable/icon')

Yet another Googlemare Landmine.... Somehow, if you mess up, the icon line on your .gen file dies. (Empirical proof of mine after struggling 2 hours)

Insert a new icon 72x72 icon on the hdpi folder with a different name from the original, and update the name on the manifest also.

The icon somehow resurrects on the Gen file and voila!! time to move on.

Set time to 00:00:00

One more JAVA 8 way:

LocalDateTime localDateTime =;

But it's a lot more useful to edit the date that already exists.

Facebook key hash does not match any stored key hashes

After hours of trying I've finally found a solution.

  1. Delete any app on the website of Facebook (
  2. Delete the file debug.keystore under C:\Users\yourUserName\.android
  3. Generate a new key (by running your app again)
  4. Create a new app on and add the new hash key
  5. Re-run your app
  6. Succes!

How to change the remote repository for a git submodule?

With Git 2.25 (Q1 2020), you can modify it.
See "Git submodule url changed" and the new command

git submodule set-url [--] <path> <newurl>

Original answer (May 2009, ten years ago)

Actually, a patch has been submitted in April 2009 to clarify gitmodule role.

So now the gitmodule documentation does not yet include:

The .gitmodules file, located in the top-level directory of a git working tree, is a text file with a syntax matching the requirements -of linkgit:git-config1.
As this file is managed by Git, it tracks the +records of a project's submodules.
Information stored in this file is used as a hint to prime the authoritative version of the record stored in the project configuration file.
User specific record changes (e.g. to account for differences in submodule URLs due to networking situations) should be made to the configuration file, while record changes to be propagated (e.g. +due to a relocation of the submodule source) should be made to this file.

That pretty much confirm Jim's answer.

If you follow this git submodule tutorial, you see you need a "git submodule init" to add the submodule repository URLs to .git/config.

"git submodule sync" has been added in August 2008 precisely to make that task easier when URL changes (especially if the number of submodules is important).
The associate script with that command is straightforward enough:

module_list "$@" |
while read mode sha1 stage path
    name=$(module_name "$path")
    url=$(git config -f .gitmodules --get submodule."$name".url)
    if test -e "$path"/.git
        unset GIT_DIR
        cd "$path"
        say "Synchronizing submodule url for '$name'"
        git config remote."$remote".url "$url"

The goal remains: git config remote."$remote".url "$url"

How to read input from console in a batch file?

The code snippet in the linked proposed duplicate reads user input.

ECHO A current build of Test Harness exists.
set /p delBuild=Delete preexisting build [y/n]?: 

The user can type as many letters as they want, and it will go into the delBuild variable.

Check if value exists in column in VBA

The find method of a range is faster than using a for loop to loop through all the cells manually.

here is an example of using the find method in vba

Sub Find_First()
Dim FindString As String
Dim Rng As Range
FindString = InputBox("Enter a Search value")
If Trim(FindString) <> "" Then
    With Sheets("Sheet1").Range("A:A") 'searches all of column A
        Set Rng = .Find(What:=FindString, _
                        After:=.Cells(.Cells.Count), _
                        LookIn:=xlValues, _
                        LookAt:=xlWhole, _
                        SearchOrder:=xlByRows, _
                        SearchDirection:=xlNext, _
        If Not Rng Is Nothing Then
            Application.Goto Rng, True 'value found
            MsgBox "Nothing found" 'value not found
        End If
    End With
End If
End Sub

List submodules in a Git repository

If there isn't any .gitmodules file, but a submodules configuration exists in .git/modules/:

find .git/modules/ -name config -exec grep url {} \;

Scanner method to get a char the method of entering character by user based on the number entered at the run time


Scraping data from website using vba

Other methods were mentioned so let us please acknowledge that, at the time of writing, we are in the 21st century. Let's park the local bus browser opening, and fly with an XMLHTTP GET request (XHR GET for short).

Wiki moment:

XHR is an API in the form of an object whose methods transfer data between a web browser and a web server. The object is provided by the browser's JavaScript environment

It's a fast method for retrieving data that doesn't require opening a browser. The server response can be read into an HTMLDocument and the process of grabbing the table continued from there.

Note that javascript rendered/dynamically added content will not be retrieved as there is no javascript engine running (which there is in a browser).

In the below code, the table is grabbed by its id cr1.


In the helper sub, WriteTable, we loop the columns (td tags) and then the table rows (tr tags), and finally traverse the length of each table row, table cell by table cell. As we only want data from columns 1 and 8, a Select Case statement is used specify what is written out to the sheet.

Sample webpage view:

Sample page view

Sample code output:

Code output


Option Explicit
Public Sub GetRates()
    Dim html As HTMLDocument, hTable As HTMLTable '<== Tools > References > Microsoft HTML Object Library
    Set html = New HTMLDocument
    With CreateObject("MSXML2.XMLHTTP")
        .Open "GET", "", False
        .setRequestHeader "If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT" 'to deal with potential caching
        html.body.innerHTML = .responseText
    End With
    Application.ScreenUpdating = False
    Set hTable = html.getElementById("cr1")
    WriteTable hTable, 1, ThisWorkbook.Worksheets("Sheet1")
    Application.ScreenUpdating = True
End Sub

Public Sub WriteTable(ByVal hTable As HTMLTable, Optional ByVal startRow As Long = 1, Optional ByVal ws As Worksheet)
    Dim tSection As Object, tRow As Object, tCell As Object, tr As Object, td As Object, r As Long, C As Long, tBody As Object
    r = startRow: If ws Is Nothing Then Set ws = ActiveSheet
    With ws
        Dim headers As Object, header As Object, columnCounter As Long
        Set headers = hTable.getElementsByTagName("th")
        For Each header In headers
            columnCounter = columnCounter + 1
            Select Case columnCounter
            Case 2
                .Cells(startRow, 1) = header.innerText
            Case 8
                .Cells(startRow, 2) = header.innerText
            End Select
        Next header
        startRow = startRow + 1
        Set tBody = hTable.getElementsByTagName("tbody")
        For Each tSection In tBody
            Set tRow = tSection.getElementsByTagName("tr")
            For Each tr In tRow
                r = r + 1
                Set tCell = tr.getElementsByTagName("td")
                C = 1
                For Each td In tCell
                    Select Case C
                    Case 2
                        .Cells(r, 1).Value = td.innerText
                    Case 8
                        .Cells(r, 2).Value = td.innerText
                    End Select
                    C = C + 1
                Next td
            Next tr
        Next tSection
    End With
End Sub

openpyxl - adjust column width size

You could estimate (or use a mono width font) to achieve this. Let's assume data is a nested array like [['a1','a2'],['b1','b2']]

We can get the max characters in each column. Then set the width to that. Width is exactly the width of a monospace font (if not changing other styles at least). Even if you use a variable width font it is a decent estimation. This will not work with formulas.

from openpyxl.utils import get_column_letter

column_widths = []
for row in data:
    for i, cell in enumerate(row):
        if len(column_widths) > i:
            if len(cell) > column_widths[i]:
                column_widths[i] = len(cell)
            column_widths += [len(cell)]

for i, column_width in enumerate(column_widths):
    worksheet.column_dimensions[get_column_letter(i+1)].width = column_width

A bit of a hack but your reports will be more readable.

How to print a dictionary's key?

Try this:

def name_the_key(dict, key):
    return key, dict[key]

mydict = {'key1':1, 'key2':2, 'key3':3}

key_name, value = name_the_key(mydict, 'key2')
print 'KEY NAME: %s' % key_name
print 'KEY VALUE: %s' % value

Split page vertically using CSS

Just add overflow:auto; to parent div

<div style="width: 100%;overflow:auto;">
    <div style="float:left; width: 80%">
    <div style="float:right;">

Working Demo

Apache: Restrict access to specific source IP inside virtual host

In Apache 2.4, the authorization configuration syntax has changed, and the Order, Deny or Allow directives should no longer be used.

The new way to do this would be:

<VirtualHost *:8080>
    <Location />
        Require ip

Further examples using the new syntax can be found in the Apache documentation: Upgrading to 2.4 from 2.2

How to execute mongo commands through shell scripts?

I use the "heredoc" syntax, which David Young mentions. But there is a catch:


mongo <db> <<EOF
  fieldName: { $exists: true }
.forEach( printjson );

The above will NOT work, because the phrase "$exists" will be seen by the shell and substituted with the value of the environment variable named "exists." Which, likely, doesn't exist, so after shell expansion, it becomes:


mongo <db> <<EOF
  fieldName: { : true }
.forEach( printjson );

In order to have it pass through you have two options. One is ugly, one is quite nice. First, the ugly one: escape the $ signs:


mongo <db> <<EOF
  fieldName: { \$exists: true }
.forEach( printjson );

I do NOT recommend this, because it is easy to forget to escape.

The other option is to escape the EOF, like this:


mongo <db> <<\EOF
  fieldName: { $exists: true }
.forEach( printjson );

Now, you can put all the dollar signs you want in your heredoc, and the dollar signs are ignored. The down side: That doesn't work if you need to put shell parameters/variables in your mongo script.

Another option you can play with is to mess with your shebang. For example,

#!/bin/env mongo
<some mongo stuff>

There are several problems with this solution:

  1. It only works if you are trying to make a mongo shell script executable from the command line. You can't mix regular shell commands with mongo shell commands. And all you save by doing so is not having to type "mongo" on the command line... (reason enough, of course)

  2. It functions exactly like "mongo <some-js-file>" which means it does not let you use the "use <db>" command.

I have tried adding the database name to the shebang, which you would think would work. Unfortunately, the way the system processes the shebang line, everything after the first space is passed as a single parameter (as if quoted) to the env command, and env fails to find and run it.

Instead, you have to embed the database change within the script itself, like so:

#!/bin/env mongo
db = db.getSiblingDB('<db>');
<your script>

As with anything in life, "there is more than one way to do it!"

Iterate through a C++ Vector using a 'for' loop

Here is a simpler way to iterate and print values in vector.

for(int x: A) // for integer x in vector A
    cout<< x <<" "; 

List comprehension on a nested list?

Yes, you can do it with such a code:

l = [[float(y) for y in x] for x in l]

iterrows pandas get next rows value

Firstly, your "messy way" is ok, there's nothing wrong with using indices into the dataframe, and this will not be too slow. iterrows() itself isn't terribly fast.

A version of your first idea that would work would be:

row_iterator = df.iterrows()
_, last =  # take first item from row_iterator
for i, row in row_iterator:
    last = row

The second method could do something similar, to save one index into the dataframe:

last = df.irow(0)
for i in range(1, df.shape[0]):
    last = df.irow(i)

When speed is critical you can always try both and time the code.

Storing Images in DB - Yea or Nay?

Another benefit of storing the images in the file system is that you don't have to do anything special to have the client cache them...

...unless of course the image isn't accessible via the document root (e.g. authentication barrier), in which case you'll need to check the cache-control headers your code is sending.

How do I return the response from an asynchronous call?

ECMAScript 6 has 'generators' which allow you to easily program in an asynchronous style.

function* myGenerator() {
    const callback = yield;
    let [response] = yield $.ajax("", {complete: callback});
    console.log("response is:", response);

    // examples of other things you can do
    yield setTimeout(callback, 1000);
    console.log("it delayed for 1000ms");
    while (response.statusText === "error") {
        [response] = yield* anotherGenerator();

To run the above code you do this:

const gen = myGenerator(); // Create generator; // Start it =>[...args])); // Set its callback function

If you need to target browsers that don't support ES6 you can run the code through Babel or closure-compiler to generate ECMAScript 5.

The callback ...args are wrapped in an array and destructured when you read them so that the pattern can cope with callbacks that have multiple arguments. For example with node fs:

const [err, data] = yield fs.readFile(filePath, "utf-8", callback);

execute function after complete page load

Alternatively you can try below.

$(window).bind("load", function() { 
// code here });

This works in all the case. This will trigger only when the entire page is loaded.

Best way to replace multiple characters in a string?

Maybe a simple loop for chars to replace:

a = '&#'

to_replace = ['&', '#']

for char in to_replace:
    a = a.replace(char, "\\"+char)


>>> \&\#

How to log PostgreSQL queries?

Edit your /etc/postgresql/9.3/main/postgresql.conf, and change the lines as follows.

Note: If you didn't find the postgresql.conf file, then just type $locate postgresql.conf in a terminal

  1. #log_directory = 'pg_log' to log_directory = 'pg_log'

  2. #log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' to log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'

  3. #log_statement = 'none' to log_statement = 'all'

  4. #logging_collector = off to logging_collector = on

  5. Optional: SELECT set_config('log_statement', 'all', true);

  6. sudo /etc/init.d/postgresql restart or sudo service postgresql restart

  7. Fire query in postgresql select 2+2

  8. Find current log in /var/lib/pgsql/9.2/data/pg_log/

The log files tend to grow a lot over a time, and might kill your machine. For your safety, write a bash script that'll delete logs and restart postgresql server.

Thanks @paul , @Jarret Hardie , @Zoltán , @Rix Beck , @Latif Premani

How to use classes from .jar files?

As workmad3 says, you need the jar file to be in your classpath. If you're compiling from the commandline, that will mean using the -classpath flag. (Avoid the CLASSPATH environment variable; it's a pain in the neck IMO.)

If you're using an IDE, please let us know which one and we can help you with the steps specific to that IDE.

Joining two table entities in Spring Data JPA

For a typical example of employees owning one or more phones, see this wikibook section.

For your specific example, if you want to do a one-to-one relationship, you should change the next code in ReleaseDateType model:

@Column(nullable = true) 
private Integer media_Id;


@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name="CACHE_MEDIA_ID", nullable=true)
private CacheMedia cacheMedia ;

and in CacheMedia model you need to add:

@OneToOne(cascade=ALL, mappedBy="ReleaseDateType")
private ReleaseDateType releaseDateType;

then in your repository you should replace:

@Query("Select * from A a  left join B b on")
public List<ReleaseDateType> FindAllWithDescriptionQuery();


//In this case a query annotation is not need since spring constructs the query from the method name
public List<ReleaseDateType> findByCacheMedia_Id(Integer id); 

or by:

@Query("FROM ReleaseDateType AS rdt WHERE = ?1")    //This is using a named query method
public List<ReleaseDateType> FindAllWithDescriptionQuery(Integer id);

Or if you prefer to do a @OneToMany and @ManyToOne relation, you should change the next code in ReleaseDateType model:

@Column(nullable = true) 
private Integer media_Id;


@OneToMany(cascade=ALL, mappedBy="ReleaseDateType")
private List<CacheMedia> cacheMedias ;

and in CacheMedia model you need to add:

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name="RELEASE_DATE_TYPE_ID", nullable=true)
private ReleaseDateType releaseDateType;

then in your repository you should replace:

@Query("Select * from A a  left join B b on")
public List<ReleaseDateType> FindAllWithDescriptionQuery();


//In this case a query annotation is not need since spring constructs the query from the method name
public List<ReleaseDateType> findByCacheMedias_Id(Integer id); 

or by:

@Query("FROM ReleaseDateType AS rdt LEFT JOIN rdt.cacheMedias AS cm WHERE = ?1")    //This is using a named query method
public List<ReleaseDateType> FindAllWithDescriptionQuery(Integer id);

How to decrease prod bundle size?

Another way to reduce bundle, is to serve GZIP instead of JS. We went from 2.6mb to 543ko.

Getting all selected checkboxes in an array

In MooTools 1.3 (latest at the time of writing):

var array = [];
    array.push( i.value );

How to check if field is null or empty in MySQL?

Try using nullif:

SELECT ifnull(nullif(field1,''),'empty') AS field1
  FROM tablename;

How to remove illegal characters from path and filenames?

I think it is much easier to validate using a regex and specifiing which characters are allowed, instead of trying to check for all bad characters. See these links:

Also, do a search for "regular expression editor"s, they help a lot. There are some around which even output the code in c# for you.

Android textview usage as label and value

You should implement a Custom List View, such that you define a Layout once and draw it for every row in the list view.

openssl s_client -cert: Proving a client certificate was sent to the server

In order to verify a client certificate is being sent to the server, you need to analyze the output from the combination of the -state and -debug flags.

First as a baseline, try running

$ openssl s_client -connect host:443 -state -debug

You'll get a ton of output, but the lines we are interested in look like this:

SSL_connect:SSLv3 read server done A
write to 0x211efb0 [0x21ced50] (12 bytes => 12 (0xC))
0000 - 16 03 01 00 07 0b 00 00-03                        .........
000c - <SPACES/NULS>
SSL_connect:SSLv3 write client certificate A

What's happening here:

  • The -state flag is responsible for displaying the end of the previous section:

    SSL_connect:SSLv3 read server done A  

    This is only important for helping you find your place in the output.

  • Then the -debug flag is showing the raw bytes being sent in the next step:

    write to 0x211efb0 [0x21ced50] (12 bytes => 12 (0xC))
    0000 - 16 03 01 00 07 0b 00 00-03                        .........
    000c - <SPACES/NULS>
  • Finally, the -state flag is once again reporting the result of the step that -debug just echoed:

    SSL_connect:SSLv3 write client certificate A

So in other words: s_client finished reading data sent from the server, and sent 12 bytes to the server as (what I assume is) a "no client certificate" message.

If you repeat the test, but this time include the -cert and -key flags like this:

$ openssl s_client -connect host:443 \
   -cert cert_and_key.pem \
   -key cert_and_key.pem  \
   -state -debug

your output between the "read server done" line and the "write client certificate" line will be much longer, representing the binary form of your client certificate:

SSL_connect:SSLv3 read server done A
write to 0x7bd970 [0x86d890] (1576 bytes => 1576 (0x628))
0000 - 16 03 01 06 23 0b 00 06-1f 00 06 1c 00 06 19 31   ....#..........1
0620 - 95 ca 5e f4 2f 6c 43 11-                          ..^%/lC.
SSL_connect:SSLv3 write client certificate A

The 1576 bytes is an excellent indication on its own that the cert was transmitted, but on top of that, the right-hand column will show parts of the certificate that are human-readable: You should be able to recognize the CN and issuer strings of your cert in there.

How do I see the commit differences between branches in git?

I'd suggest the following to see the difference "in commits". For symmetric difference, repeat the command with inverted args:

git cherry -v master [your branch, or HEAD as default]

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

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

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

How can I convert a date to GMT?

After searching for an hour or two ,I've found a simple solution below.

const date = new Date(`${date from client} GMT`);

inside double ticks, there is a date from client side plust GMT.

I'm first time commenting, constructive criticism will be welcomed.

Call a global variable inside module

You need to tell the compiler it has been declared:

declare var bootbox: any;

If you have better type information you can add that too, in place of any.

How do I code my submit button go to an email address

You might use Form tag with action attribute to submit the mailto.

Here is an example:

<form method="post" action="mailto:[email protected]" >
<input type="submit" value="Send Email" /> 

Finding sum of elements in Swift array

Keep it simple...

var array = [1, 2, 3, 4, 5, 6, 7, 9, 0]
var n = 0
for i in array {
    n += i
print("My sum of elements is: \(n)")


My sum of elements is: 37

python 2.7: cannot pip on windows "bash: pip: command not found"

On Windows, pip lives in C:\[pythondir]\scripts.

So you'll need to add that to your system path in order to run it from the command prompt. You could alternatively cd into that directory each time, but that's a hassle.

See the top answer here for info on how to do that: Adding Python Path on Windows 7

Also, that is a terrifying way to install pip. Grab it from Christophe Gohlke. Grab everything else from there for that matter.

Checking host availability by using ping in bash scripts

I liked the idea of checking a list like:

for i in `cat Hostlist`
  ping -c1 -w2 $i | grep "PING" | awk '{print $2,$3}'

but that snippet doesn't care if a host is unreachable, so is not a great answer IMHO.

I ran with it and wrote

for i in `cat Hostlist`
  ping -c1 -w2 $i >/dev/null 2>&1 ; echo $i $?

And I can then handle each accordingly.

How to get anchor text/href on click using jQuery?

Without jQuery:

You don't need jQuery when it is so simple to do this using pure JavaScript. Here are two options:

  • Method 1 - Retrieve the exact value of the href attribute:

    Select the element and then use the .getAttribute() method.

    This method does not return the full URL, instead it retrieves the exact value of the href attribute.

    var anchor = document.querySelector('a'),_x000D_
        url = anchor.getAttribute('href');_x000D_
    <a href="/relative/path.html"></a>

  • Method 2 - Retrieve the full URL path:

    Select the element and then simply access the href property.

    This method returns the full URL path.

    In this case:

    var anchor = document.querySelector('a'),_x000D_
        url = anchor.href;_x000D_
    <a href="/relative/path.html"></a>

As your title implies, you want to get the href value on click. Simply select an element, add a click event listener and then return the href value using either of the aforementioned methods.

var anchor = document.querySelector('a'),_x000D_
    button = document.getElementById('getURL'),_x000D_
    url = anchor.href;_x000D_
button.addEventListener('click', function (e) {_x000D_
<button id="getURL">Click me!</button>_x000D_
<a href="/relative/path.html"></a>

Error: unmappable character for encoding UTF8 during maven compilation

Set incodign attribute in maven-compiler plugin work for me. The code example is the following


how to convert a string date to date format in oracle10g

You need to use the TO_DATE function.


Get client IP address via third party web service

        url: '//',
        type: 'POST',
        dataType: 'jsonp',
        success: function(location) {

This will work https too

GoogleMaps API KEY for testing

There seems no way to have google maps api key free without credit card. To test the functionality of google map you can use it while leaving the api key field "EMPTY". It will show a message saying "For Development Purpose Only". And that way you can test google map functionality without putting billing information for google map api key.

<script src="" async defer></script>

WARNING in budgets, maximum exceeded for initial

What is Angular CLI Budgets? Budgets is one of the less known features of the Angular CLI. It’s a rather small but a very neat feature!

As applications grow in functionality, they also grow in size. Budgets is a feature in the Angular CLI which allows you to set budget thresholds in your configuration to ensure parts of your application stay within boundaries which you setOfficial Documentation

Or in other words, we can describe our Angular application as a set of compiled JavaScript files called bundles which are produced by the build process. Angular budgets allows us to configure expected sizes of these bundles. More so, we can configure thresholds for conditions when we want to receive a warning or even fail build with an error if the bundle size gets too out of control!

How To Define A Budget? Angular budgets are defined in the angular.json file. Budgets are defined per project which makes sense because every app in a workspace has different needs.

Thinking pragmatically, it only makes sense to define budgets for the production builds. Prod build creates bundles with “true size” after applying all optimizations like tree-shaking and code minimization.

Oops, a build error! The maximum bundle size was exceeded. This is a great signal that tells us that something went wrong…

  1. We might have experimented in our feature and didn’t clean up properly
  2. Our tooling can go wrong and perform a bad auto-import, or we pick bad item from the suggested list of imports
  3. We might import stuff from lazy modules in inappropriate locations
  4. Our new feature is just really big and doesn’t fit into existing budgets

First Approach: Are your files gzipped?

Generally speaking, gzipped file has only about 20% the size of the original file, which can drastically decrease the initial load time of your app. To check if you have gzipped your files, just open the network tab of developer console. In the “Response Headers”, if you should see “Content-Encoding: gzip”, you are good to go.

How to gzip? If you host your Angular app in most of the cloud platforms or CDN, you should not worry about this issue as they probably have handled this for you. However, if you have your own server (such as NodeJS + expressJS) serving your Angular app, definitely check if the files are gzipped. The following is an example to gzip your static assets in a NodeJS + expressJS app. You can hardly imagine this dead simple middleware “compression” would reduce your bundle size from 2.21MB to 495.13KB.

const compression = require('compression')
const express = require('express')
const app = express()

Second Approach:: Analyze your Angular bundle

If your bundle size does get too big you may want to analyze your bundle because you may have used an inappropriate large-sized third party package or you forgot to remove some package if you are not using it anymore. Webpack has an amazing feature to give us a visual idea of the composition of a webpack bundle.

enter image description here

It’s super easy to get this graph.

  1. npm install -g webpack-bundle-analyzer
  2. In your Angular app, run ng build --stats-json (don’t use flag --prod). By enabling --stats-json you will get an additional file stats.json
  3. Finally, run webpack-bundle-analyzer ./dist/stats.json and your browser will pop up the page at localhost:8888. Have fun with it.

ref 1: How Did Angular CLI Budgets Save My Day And How They Can Save Yours

ref 2: Optimize Angular bundle size in 4 steps

Add a linebreak in an HTML text area

I believe this will work:

TextArea.Text = "Line 1" & vbCrLf & "Line 2"

System.Environment.NewLine could be used in place of vbCrLf if you wanted to be a little less VB6 about it.

Placeholder in UITextView

I was able to do add a "place holder" to a UITextView with ALOT less code. This is what I did:

UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(60, 800, 200, 60)];
textView.text = @"Write characters here...";
textView.textColor=[UIColor grayColor];
textView.font = [UIFont fontWithName:@"Hevlatica" size:15];

I guess it's not an actual placeholder because you have to delete the text before you write but it could help if you wanted something a bit more simple.

Postgresql SQL: How check boolean field with null and True,False Value?

There are 3 states for boolean in PG: true, false and unknown (null). Explained here: Postgres boolean datatype

Therefore you need only query for NOT TRUE:

SELECT * from table_name WHERE boolean_column IS NOT TRUE;

Deserialize JSON string to c# object

I believe you are looking for this:

string str = "{\"Arg1\":\"Arg1Value\",\"Arg2\":\"Arg2Value\"}";
JavaScriptSerializer serializer1 = new JavaScriptSerializer();
object obje = serializer1.Deserialize(str, obj1.GetType());

Lazy Method for Reading Big File in Python?

I'm in a somewhat similar situation. It's not clear whether you know chunk size in bytes; I usually don't, but the number of records (lines) that is required is known:

def get_line():
     with open('4gb_file') as file:
         for i in file:
             yield i

lines_required = 100
gen = get_line()
chunk = [i for i, j in zip(gen, range(lines_required))]

Update: Thanks nosklo. Here's what I meant. It almost works, except that it loses a line 'between' chunks.

chunk = [next(gen) for i in range(lines_required)]

Does the trick w/o losing any lines, but it doesn't look very nice.

C++ Matrix Class

There is no "canonical" way to do the matrix in C++, STL does not provide classes like "matrix". However there are some 3rd party libraries that do. You are encouraged to use them or write your own implementation. You can try my implementation derived from some public implementation found on the internet.

undefined reference to `WinMain@16'

I was encountering this error while compiling my application with SDL. This was caused by SDL defining it's own main function in SDL_main.h. To prevent SDL define the main function an SDL_MAIN_HANDLED macro has to be defined before the SDL.h header is included.

What does $_ mean in PowerShell?

$_ is an alias for automatic variable $PSItem (introduced in PowerShell V3.0; Usage information found here) which represents the current item from the pipe.

PowerShell (v6.0) online documentation for automatic variables is here.

Postgresql, update if row with some unique value exists, else insert

I found this post more relevant in this scenario:

WITH upsert AS (
     UPDATE spider_count SET tally=tally+1 
     WHERE date='today' AND spider='Googlebot' 
INSERT INTO spider_count (spider, tally) 
SELECT 'Googlebot', 1 

NodeJS: How to decode base64 encoded string back to binary?

As of Node.js v6.0.0 using the constructor method has been deprecated and the following method should instead be used to construct a new buffer from a base64 encoded string:

var b64string = /* whatever */;
var buf = Buffer.from(b64string, 'base64'); // Ta-da

For Node.js v5.11.1 and below

Construct a new Buffer and pass 'base64' as the second argument:

var b64string = /* whatever */;
var buf = new Buffer(b64string, 'base64'); // Ta-da

If you want to be clean, you can check whether from exists :

if (typeof Buffer.from === "function") {
    // Node 5.10+
    buf = Buffer.from(b64string, 'base64'); // Ta-da
} else {
    // older Node versions, now deprecated
    buf = new Buffer(b64string, 'base64'); // Ta-da

Define variable to use with IN operator (T-SQL)

I think you'll have to declare a string and then execute that SQL string.

Have a look at sp_executeSQL

What does print(... sep='', '\t' ) mean?

sep='' ignore whiteSpace. see the code to understand.Without sep=''

from itertools import permutations
s,k = input().split()
for i in list(permutations(sorted(s), int(k))):



using sep='' The code and output.

from itertools import permutations
s,k = input().split()
for i in list(permutations(sorted(s), int(k))):



Which data structures and algorithms book should I buy?

If you want the algorithms to be implemented specifically in Java then there is Mitchell Waite's Series book "Data Structures & Algorithms in Java". It starts from basic data structures like linked lists, stacks and queues, and the basic algorithms for sorting and searching. Working your way through it you will eventually get to Tree data structures, Red-Black trees, 2-3 trees and Graphs.

All-in-all its not an extremely theoretical book, but if you just want an introduction in a language you are familiar with then its a good book. At the end of the day, if you want a deeper understanding of algorithms you're going to have to learn some of the more theoretical concepts, and read one of the classics, like Cormen/Leiserson/Rivest/Stein's Introduction to Algorithms.

how to set radio option checked onload with jQuery

De esta forma Jquery obtiene solo el elemento checked


How to localise a string inside the iOS info.plist file?

When using InfoPlist.strings file (in XCode it should be placed next to Info.plist file - real file location can be anywhere within the project probably

View in XCode

) be careful to use the key's short name for the translation.

I was trying to use Privacy - Camera Usage Description, but the working key is NSCameraUsageDescription

jQuery - Increase the value of a counter when a button is clicked

You cannot use ++ on something which is not a variable, this would be the closest you can get:

$('#counter').html(function(i, val) { return +val+1 });

jQuery's html() method can get and set the HTML value of an element. If passed a function it can update the HTML based upon the existing value. So in the context of your code:

$("#update").click(function() {
    $('#counter').html(function(i, val) { return +val+1 });


When it comes to synchronising your counter on the page, with the counter value in your database, never trust the client! You send either an increment or decrement signal to you server side script, rather than a continuous value such as 10, or 23.

However you could send an AJAX request to the server when you change the HTML of your counter:

$("#update").click(function() {
    $('#counter').html(function(i, val) {
            url: '/path/to/script/',
            type: 'POST',
            data: {increment: true},
            success: function() { alert('Request has returned') }
        return +val+1;

Best way to get user GPS location in background in Android

I have try to my code and got success try this

package com.mobeyosoft.latitudelongitude;

import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;

 * Created by 5943 6417 on 14-09-2016.
public class LocationService extends Service
    public static final String BROADCAST_ACTION = "Hello World";
    private static final int TWO_MINUTES = 1000 * 60 * 1;
    public LocationManager locationManager;
    public MyLocationListener listener;
    public Location previousBestLocation = null;

    Context context;

    Intent intent;
    int counter = 0;

    public void onCreate() {
        intent = new Intent(BROADCAST_ACTION);

    public void onStart(Intent intent, int startId) {
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        listener = new MyLocationListener();
        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 4000, 0, listener);
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 4000, 0, listener);

    public IBinder onBind(Intent intent){
        return null;

    protected boolean isBetterLocation(Location location, Location currentBestLocation) {
        if (currentBestLocation == null) {
            // A new location is always better than no location
            return true;

        // Check whether the new location fix is newer or older
        long timeDelta = location.getTime() - currentBestLocation.getTime();
        boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
        boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
        boolean isNewer = timeDelta > 0;

        // If it's been more than two minutes since the current location, use the new location
        // because the user has likely moved
        if (isSignificantlyNewer) {
            return true;
            // If the new location is more than two minutes older, it must be worse
        } else if (isSignificantlyOlder) {
            return false;

        // Check whether the new location fix is more or less accurate
        int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy());
        boolean isLessAccurate = accuracyDelta > 0;
        boolean isMoreAccurate = accuracyDelta < 0;
        boolean isSignificantlyLessAccurate = accuracyDelta > 200;

        // Check if the old and new location are from the same provider
        boolean isFromSameProvider = isSameProvider(location.getProvider(),

        // Determine location quality using a combination of timeliness and accuracy
        if (isMoreAccurate) {
            return true;
        } else if (isNewer && !isLessAccurate) {
            return true;
        } else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
            return true;
        return false;

    /** Checks whether two providers are the same */
    private boolean isSameProvider(String provider1, String provider2) {
        if (provider1 == null) {
            return provider2 == null;
        return provider1.equals(provider2);

    public void onDestroy() {
        // handler.removeCallbacks(sendUpdatesToUI);
        Log.v("STOP_SERVICE", "DONE");

    public static Thread performOnBackgroundThread(final Runnable runnable) {
        final Thread t = new Thread() {
            public void run() {
                try {
                } finally {

        return t;

    public class MyLocationListener implements LocationListener{

        public void onLocationChanged(final Location loc)
            Log.i("**********", "Location changed");
            if(isBetterLocation(loc, previousBestLocation)) {
                Toast.makeText(context, "Latitude" + loc.getLatitude() + "\nLongitude"+loc.getLongitude(),Toast.LENGTH_SHORT).show();
                intent.putExtra("Latitude", loc.getLatitude());
                intent.putExtra("Longitude", loc.getLongitude());
                intent.putExtra("Provider", loc.getProvider());


        public void onProviderDisabled(String provider)
            Toast.makeText( getApplicationContext(), "Gps Disabled", Toast.LENGTH_SHORT ).show();

        public void onProviderEnabled(String provider)
            Toast.makeText( getApplicationContext(), "Gps Enabled", Toast.LENGTH_SHORT).show();

        public void onStatusChanged(String provider, int status, Bundle extras)



ERROR Source option 1.5 is no longer supported. Use 1.6 or later

I got this error: "Source option 5 is no longer supported. Use 6 or later" after I changed the pom.xml




Later to realise the property was used with a dash insteal of a dot:


(swearings), I replaced the dot with a dash and the error went away:


2D arrays in Python

def enter(n):
    for i in  range(0,n):
        y.append(int(input("Enter ")))
    return y
for i in range(0,2):
print (x)

here i made function to create 1-D array and inserted into another array as a array member. multiple 1-d array inside a an array, as the value of n and i changes u create multi dimensional arrays

How do I set up NSZombieEnabled in Xcode 4?

Jano's answer is the easiest way to find it.. another way would be if you click on the scheme drop down bar -> edit scheme -> arguments tab and then add NSZombieEnabled in the Environment Variables column and YES in the value column...

Count immediate child div elements using jQuery

$("#foo > div").length

Direct children of the element with the id 'foo' which are divs. Then retrieving the size of the wrapped set produced.

Maven: Failed to read artifact descriptor

I had the same problem for a while and despite doing mvn -U clean install the problem was not getting solved!

I finally solved the problem by deleting the whole .m2 folder and then restarted my IDE and the problem was gone!

So sometimes the problem would rise because of some incompatibilities or problems in your local maven repository.

How do you create an asynchronous method in C#?

One very simple way to make a method asynchronous is to use Task.Yield() method. As MSDN states:

You can use await Task.Yield(); in an asynchronous method to force the method to complete asynchronously.

Insert it at beginning of your method and it will then return immediately to the caller and complete the rest of the method on another thread.

private async Task<DateTime> CountToAsync(int num = 1000)
    await Task.Yield();
    for (int i = 0; i < num; i++)
        Console.WriteLine("#{0}", i);
    return DateTime.Now;

Bubble Sort Homework

arr = [5,4,3,1,6,8,10,9] # array not sorted

for i in range(len(arr)):
    for j in range(i, len(arr)):
        if(arr[i] > arr[j]):
            arr[i], arr[j] = arr[j], arr[i]

            print (arr)

Stop form from submitting , Using Jquery

Again, AJAX is async. So the showMsg function will be called only after success response from the server.. and the form submit event will not wait until AJAX success.

Move the e.preventDefault(); as first line in the click handler.

$("form").submit(function (e) {
      e.preventDefault(); // this will prevent from submitting the form.

See below code,

I want it to be allowed HasJobInProgress == False

$(document).ready(function () {
    $("form").submit(function (e) {
        e.preventDefault(); //prevent default form submit
            url: '@Url.Action("HasJobInProgress", "ClientChoices")/',
            data: { id: '@Model.ClientId' },
            success: function (data) {
            cache: false
$("#cancelButton").click(function () {
    window.location = '@Url.Action("list", "default", new { clientId = Model.ClientId })';
$("[type=text]").focus(function () {
function showMsg(hasCurrentJob) {
    if (hasCurrentJob == "True") {
        alert("The current clients has a job in progress. No changes can be saved until current job completes");
        return false;
    } else {

PHP Multiple Checkbox Array

add [] in the name of the attributes in the input tag

 <form action="" name="frm" method="post">
<input type="checkbox" name="hobby[]" value="coding">  coding &nbsp
<input type="checkbox" name="hobby[]" value="database">  database &nbsp
<input type="checkbox" name="hobby[]" value="software engineer">  soft Engineering <br>
<input type="submit" name="submit" value="submit"> 

for PHP Code :

   $hobby = $_POST['hobby'];

   foreach ($hobby as $hobys=>$value) {
             echo "Hobby : ".$value."<br />";

How do I get a class instance of generic type T?

A standard approach/workaround/solution is to add a class object to the constructor(s), like:

 public class Foo<T> {

    private Class<T> type;
    public Foo(Class<T> type) {
      this.type = type;

    public Class<T> getType() {
      return type;

    public T newInstance() {
      return type.newInstance();

Import error No module named skimage

You can use pip install scikit-image.

Also see the recommended procedure.

decompiling DEX into Java sourcecode

It's easy

Get these tools:

  1. dex2jar to translate dex files to jar files

  2. jd-gui to view the java files in the jar

The source code is quite readable as dex2jar makes some optimizations.


And here's the procedure on how to decompile:

Step 1:

Convert classes.dex in test_apk-debug.apk to test_apk-debug_dex2jar.jar -f -o output_jar.jar apk_to_decompile.apk -f -o output_jar.jar dex_to_decompile.dex

Note 1: In the Windows machines all the .sh scripts are replaced by .bat scripts

Note 2: On linux/mac don't forget about sh or bash. The full command should be:

sh -f -o output_jar.jar apk_to_decompile.apk 

Note 3: Also, remember to add execute permission to dex2jar-X.X directory e.g. sudo chmod -R +x dex2jar-2.0

dex2jar documentation

Step 2:

Open the jar in JD-GUI

The decompiled source

git diff between two different files

Specify the paths explicitly:

git diff HEAD:full/path/to/foo full/path/to/bar

Check out the --find-renames option in the git-diff docs.

Credit: twaggs.

what is the size of an enum type data in C++?

An enum is nearly an integer. To simplify a lot

enum yourenum { a, b, c };

is almost like

#define a 0
#define b 1
#define c 2

Of course, it is not really true. I'm trying to explain that enum are some kind of coding...

How to create UILabel programmatically using Swift?

An alternative using a closure to separate out the code into something a bit neater using Swift 4:

class theViewController: UIViewController {

    /** Create the UILabel */
    var theLabel: UILabel = {
        let label = UILabel()
        label.lineBreakMode = .byWordWrapping
        label.textColor = UIColor.white
        label.textAlignment = .left
        label.numberOfLines = 3
        label.font = UIFont(name: "Helvetica-Bold", size: 22)
        return label

    override func viewDidLoad() {
        /** Add theLabel to the ViewControllers view */

    override func viewDidLayoutSubviews() {
        /* Set the frame when the layout is changed */
        theLabel.frame = CGRect(x: 0,
                                y: 0,
                                width: view.frame.width - 30,
                                height: 24)

As a note, attributes for theLabel can still be changed whenever using functions in the VC. You're just setting various defaults inside the closure and minimizing clutter in functions like viewDidLoad()

How to build a 2 Column (Fixed - Fluid) Layout with Twitter Bootstrap?

Update 2018

Bootstrap 4

Now that BS4 is flexbox, the fixed-fluid is simple. Just set the width of the fixed column, and use the .col class on the fluid column.

.sidebar {
    width: 180px;
    min-height: 100vh;

<div class="row">
    <div class="sidebar p-2">Fixed width</div>
    <div class="col bg-dark text-white pt-2">

Bootstrap 3..

One approach to a fixed-fluid layout is using media queries that align with Bootstrap's breakpoints so that you only use the fixed width columns are larger screens and then let the layout stack responsively on smaller screens...

@media (min-width:768px) {
  #sidebar {
      min-width: 300px;
      max-width: 300px;
  #main {
      width:calc(100% - 300px);

Working Bootstrap 3 Fixed-Fluid Demo

Related Q&A:
Fixed width column with a container-fluid in bootstrap
How to left column fixed and right scrollable in Bootstrap 4, responsive?

PHP error: Notice: Undefined index:

Assure you have used method="post" in the form you are sending data from.

Open a PDF using VBA in Excel

Hope this helps. I was able to open pdf files from all subfolders of a folder and copy content to the macro enabled workbook using shell as recommended above.Please see below the code .

Sub ConsolidateWorkbooksLTD()
Dim adobeReaderPath As String
Dim pathAndFileName As String
Dim shellPathName As String
Dim fso, subFldr, subFlodr
Dim FolderPath
Dim Filename As String
Dim Sheet As Worksheet
Dim ws As Worksheet
Dim HK As String
Dim s As String
Dim J As String
Dim diaFolder As FileDialog
Dim mFolder As String
Dim Basebk As Workbook
Dim Actbk As Workbook

Application.ScreenUpdating = False

Set Basebk = ThisWorkbook

' Open the file dialog
Set diaFolder = Application.FileDialog(msoFileDialogFolderPicker)
diaFolder.AllowMultiSelect = False
MsgBox diaFolder.SelectedItems(1) & "\"
mFolder = diaFolder.SelectedItems(1) & "\"
Set diaFolder = Nothing
Set fso = CreateObject("Scripting.FileSystemObject")
Set FolderPath = fso.GetFolder(mFolder)
For Each subFldr In FolderPath.SubFolders
subFlodr = subFldr & "\"
Filename = Dir(subFldr & "\*.csv*")
Do While Len(Filename) > 0
J = Filename
J = Left(J, Len(J) - 4) & ".pdf"
   Workbooks.Open Filename:=subFldr & "\" & Filename, ReadOnly:=True
   For Each Sheet In ActiveWorkbook.Sheets
   Set Actbk = ActiveWorkbook
   s = ActiveWorkbook.Name
   HK = Left(s, Len(s) - 4)
   If InStrRev(HK, "_S") <> 0 Then
   HK = Right(HK, Len(HK) - InStrRev(HK, "_S"))
   HK = Right(HK, Len(HK) - InStrRev(HK, "_L"))
   End If
   Sheet.Copy After:=ThisWorkbook.Sheets(1)
   ActiveSheet.Name = HK

   ' Open pdf file to copy SIC Decsription
   pathAndFileName = subFlodr & J
   adobeReaderPath = "C:\Program Files (x86)\Adobe\Acrobat Reader DC\Reader\AcroRd32.exe"
   shellPathName = adobeReaderPath & " """ & pathAndFileName & """"
   Call Shell( _
    pathname:=shellPathName, _
    Application.Wait Now + TimeValue("0:00:2")

    SendKeys "%vpc"
    SendKeys "^a", True
    Application.Wait Now + TimeValue("00:00:2")

    ' send key to copy
     SendKeys "^c"
    ' wait 2 secs
     Application.Wait Now + TimeValue("00:00:2")
      ' activate this workook and paste the data
        Set ws = ThisWorkbook.Sheets(HK)

        Application.Wait Now + TimeValue("00:00:3")
        Application.CutCopyMode = False
        Application.Wait Now + TimeValue("00:00:3")
       Call Shell("TaskKill /F /IM AcroRd32.exe", vbHide)
       ' send key to close pdf file
        SendKeys "^q"
       Application.Wait Now + TimeValue("00:00:3")
 Next Sheet
 Workbooks(Filename).Close SaveAs = True
 Filename = Dir()
Application.ScreenUpdating = True
End Sub

I wrote the piece of code to copy from pdf and csv to the macro enabled workbook and you may need to fine tune as per your requirement

Regards, Hema Kasturi

Display animated GIF in iOS

Another alternative is to use a UIWebView to display the animated GIF. If the GIF is going to be fetched from a server, then this takes care of the fetching. It also works with local GIFs.

C# list.Orderby descending

list = new List<ProcedureTime>(); sortedList = list.OrderByDescending(ProcedureTime=> ProcedureTime.EndTime).ToList();

Which works for me to show the time sorted in descending order.


This happened to me when upgrading from Rails 4.0 to 4.2.

The 4.2 implementation of verified_request? looks at request.headers['X-CSRF-Token'], whereas the header my 4.0 app had been getting was X-XSRF-TOKEN. A quick fix in my ApplicationController was to add the function:

  def verify_authenticity_token
    request.headers['X-CSRF-Token'] ||= request.headers['X-XSRF-TOKEN']

Make <body> fill entire screen?

The goal is to make the <body> element take up the available height of the screen.

If you don't expect your content to take up more than the height of the screen, or you plan to make an inner scrollable element, set

body {
  height: 100vh;

otherwise, you want <body> to become scrollable when there is more content than the screen can hold, so set

body {
  min-height: 100vh;

this alone achieves the goal, albeit with a possible, and probably desirable, refinement.

Removing the margin of <body>.

body {
  margin: 0;

there are two main reasons for doing so.

  1. <body> reaches the edge of the window.
  2. <body> no longer has a scroll bar from the get-go.

P.S. if you want the background to be a radial gradient with its center in the center of the screen and not in the bottom right corner as with your example, consider using something like

body {
  min-height: 100vh;
  margin: 0;
  background: radial-gradient(circle, rgba(255,255,255,1) 0%, rgba(0,0,0,1) 100%);
<!DOCTYPE html>
<html lang="en">
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=">

Android Studio 3.0 Execution failed for task: unable to merge dex

I Have Done and fixed this issue by just doing this jobs in my code

Open ->build.gradle Change value from

compile ''


compile ''

Select value from list of tuples where condition

If you have named tuples you can do this:

results = [t.age for t in mylist if t.person_id == 10]

Otherwise use indexes:

results = [t[1] for t in mylist if t[0] == 10]

Or use tuple unpacking as per Nate's answer. Note that you don't have to give a meaningful name to every item you unpack. You can do (person_id, age, _, _, _, _) to unpack a six item tuple.

ListView with OnItemClickListener

1) Check if you are using OnItemClickListener or OnClickListener (which is not supported for ListView)
Documentation Android Developers ListView

2) Check if you added Listener to your ListView properly. It's hooked on ListView not on ListAdapter!


3) If you need to use OnClickListener, check if you do use DialogInterface.OnClickListener or View.OnClickListener (they can be easily exchanged if not validated or if using both of them)

Getting coordinates of marker in Google Maps API

One more alternative options

var map = new google.maps.Map(document.getElementById('map_canvas'), {
    zoom: 1,
    center: new google.maps.LatLng(35.137879, -82.836914),
    mapTypeId: google.maps.MapTypeId.ROADMAP

var myMarker = new google.maps.Marker({
    position: new google.maps.LatLng(47.651968, 9.478485),
    draggable: true

google.maps.event.addListener(myMarker, 'dragend', function (evt) {
    document.getElementById('current').innerHTML = '<p>Marker dropped: Current Lat: ' + + ' Current Lng: ' + evt.latLng.lng().toFixed(3) + '</p>';

google.maps.event.addListener(myMarker, 'dragstart', function (evt) {
    document.getElementById('current').innerHTML = '<p>Currently dragging marker...</p>';


and html file

        <div id='map_canvas'></div>
        <div id="current">Nothing yet...</div>

What are .dex files in Android?

About the .dex File :

One of the most remarkable features of the Dalvik Virtual Machine (the workhorse under the Android system) is that it does not use Java bytecode. Instead, a homegrown format called DEX was introduced and not even the bytecode instructions are the same as Java bytecode instructions.

Compiled Android application code file.

Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single .apk file on the device. .dex files can be created by automatically translating compiled applications written in the Java programming language.

Dex file format:

 1. File Header
 2. String Table
 3. Class List
 4. Field Table
 5. Method Table
 6. Class Definition Table
 7. Field List
 8. Method List
 9. Code Header
10. Local Variable List

Android has documentation on the Dalvik Executable Format (.dex files). You can find out more over at the official docs: Dex File Format

.dex files are similar to java class files, but they were run under the Dalkvik Virtual Machine (DVM) on older Android versions, and compiled at install time on the device to native code with ART on newer Android versions.

You can decompile .dex using the dexdump tool which is provided in android-sdk.

There are also some Reverse Engineering Techniques to make a jar file or java class file from a .dex file.

Scroll part of content in fixed position container

It seems to work if you use

div#scrollable {
    overflow-y: scroll;
    height: 100%;

and add padding-bottom: 60px to div.sidebar.

For example:

However, I am unsure why it must be 60px.

Also, you missed the f from overflow-y: scroll;

How to change the integrated terminal in visual studio code or VSCode

To change the integrated terminal on Windows, you just need to change the line:

  1. Open VS User Settings (Preferences > User Settings). This will open two side-by-side documents.
  2. Add a new "": "C:\\Bin\\Cmder\\Cmder.exe" setting to the User Settings document on the right if it's not already there. This is so you aren't editing the Default Setting directly, but instead adding to it.
  3. Save the User Settings file.

You can then access it with keys Ctrl+backtick by default.

'cannot find or open the pdb file' Visual Studio C++ 2013

No problem. You're running your code under the debugger, and the debugger is telling you that it doesn't have debugging information for the system libraries.

If you really need that (usually for stack traces), you can download it from Microsoft's symbol servers, but for now you don't need to worry.

JSON Array iteration in Android/Java

On Arrays, look for:

JSONArray menuitemArray = popupObject.getJSONArray("menuitem"); 

Execute Stored Procedure from a Function

I have figured out a solution to this problem. We can build a Function or View with "rendered" sql in a stored procedure that can then be executed as normal.

1.Create another sproc

CREATE PROCEDURE [dbo].[usp_FunctionBuilder]

2.Build the dynamic sql that you want to execute in your function (Example: you could use a loop and union, you could read in another sproc, use if statements and parameters for conditional sql, etc.)

SET @innerSql = 'your sql'

3.Wrap the @innerSql in a create function statement and define any external parameters that you have used in the @innerSql so they can be passed into the generated function.

SET @outerSql = 'CREATE FUNCTION [dbo].[fn_GeneratedFunction] ( @Param varchar(10))
' + @innerSql;


This is just pseudocode but the solution solves many problems such as linked server limitations, parameters, dynamic sql in function, dynamic server/database/table name, loops, etc.

You will need to tweak it to your needs, (Example: changing the return in the function)

How do I concatenate strings?

2020 Update: Concatenation by String Interpolation

RFC 2795 issued 2019-10-27: Suggests support for implicit arguments to do what many people would know as "string interpolation" -- a way of embedding arguments within a string to concatenate them.


Latest issue status can be found here:

At the time of this writing (2020-9-24), I believe this feature should be available in the Rust Nightly build.

This will allow you to concatenate via the following shorthand:

format_args!("hello {person}")

It is equivalent to this:

format_args!("hello {person}", person=person)

There is also the "ifmt" crate, which provides its own kind of string interpolation:

Error - SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM

DateTime.MinValue and DateTime.MaxValue

DateTime.MinValue = 1/1/0001 12:00:00 AM

DateTime.MaxValue = 23:59:59.9999999, December 31, 9999, 

                exactly one 100-nanosecond tick 

                before 00:00:00, January 1, 10000 

How do I bind to list of checkbox values with AngularJS?

A simple HTML only way of doing it:

<input type="checkbox"_x000D_
       ng-checked="fruits.indexOf('apple') > -1"_x000D_
       ng-click="fruits.indexOf('apple') > -1 ? fruits.splice(fruits.indexOf('apple'), 1) : fruits.push('apple')">_x000D_
<input type="checkbox"_x000D_
       ng-checked="fruits.indexOf('orange') > -1"_x000D_
       ng-click="fruits.indexOf('orange') > -1 ? fruits.splice(fruits.indexOf('orange'), 1) : fruits.push('orange')">_x000D_
<input type="checkbox"_x000D_
       ng-checked="fruits.indexOf('pear') > -1"_x000D_
       ng-click="fruits.indexOf('pear') > -1 ? fruits.splice(fruits.indexOf('pear'), 1) : fruits.push('pear')">_x000D_
<input type="checkbox"_x000D_
       ng-checked="fruits.indexOf('naartjie') > -1"_x000D_
       ng-click="fruits.indexOf('apple') > -1 ? fruits.splice(fruits.indexOf('apple'), 1) : fruits.push('naartjie')">

How to handle-escape both single and double quotes in an SQL-Update statement

In C# and VB the SqlCommand object implements the Parameter.AddWithValue method which handles this situation

Why dict.get(key) instead of dict[key]?

For what purpose is this function useful?

One particular usage is counting with a dictionary. Let's assume you want to count the number of occurrences of each element in a given list. The common way to do so is to make a dictionary where keys are elements and values are the number of occurrences.

fruits = ['apple', 'banana', 'peach', 'apple', 'pear']
d = {}
for fruit in fruits:
    if fruit not in d:
        d[fruit] = 0
    d[fruit] += 1

Using the .get() method, you can make this code more compact and clear:

for fruit in fruits:
    d[fruit] = d.get(fruit, 0) + 1

Getting the difference between two repositories

See, section "How to compare two local repositories" in "General".

In short you are using GIT_ALTERNATE_OBJECT_DIRECTORIES environment variable to have access to object database of the other repository, and using git rev-parse with --git-dir / GIT_DIR to convert symbolic name in other repository to SHA-1 identifier.

Modern version would look something like this (assuming that you are in 'repo_a'):

   git diff $(git --git-dir=../repo_b/.git rev-parse --verify HEAD) HEAD

where ../repo_b/.git is path to object database in repo_b (it would be repo_b.git if it were bare repository). Of course you can compare arbitrary versions, not only HEADs.

Note that if repo_a and repo_b are the same repository, it might make more sense to put both of them in the same repository, either using "git remote add -f ..." to create nickname(s) for repository for repeated updates, or obe off "git fetch ..."; as described in other responses.

How to fix "ImportError: No module named ..." error in Python?

If you have this problem when using an instaled version, when using, make sure your module is included inside packages

setup(name='Your program',
    description='Your desccription',
    packages=['foo', ''], # add `` here

How do I find the current executable filename?


How to assign a heredoc value to a variable in Bash?

this bash trick
should preserve
newlines $TEST
long live perl
echo -e $MYTEXT

Implement division with bit-wise operator

int remainder =0;

int division(int dividend, int divisor)
    int quotient = 1;

    int neg = 1;
    if ((dividend>0 &&divisor<0)||(dividend<0 && divisor>0))
        neg = -1;

    // Convert to positive
    unsigned int tempdividend = (dividend < 0) ? -dividend : dividend;
    unsigned int tempdivisor = (divisor < 0) ? -divisor : divisor;

    if (tempdivisor == tempdividend) {
        remainder = 0;
        return 1*neg;
    else if (tempdividend < tempdivisor) {
        if (dividend < 0)
            remainder = tempdividend*neg;
            remainder = tempdividend;
        return 0;
    while (tempdivisor<<1 <= tempdividend)
        tempdivisor = tempdivisor << 1;
        quotient = quotient << 1;

    // Call division recursively
    if(dividend < 0)
        quotient = quotient*neg + division(-(tempdividend-tempdivisor), divisor);
        quotient = quotient*neg + division(tempdividend-tempdivisor, divisor);
     return quotient;

void main()
    int dividend,divisor;
    char ch = 's';
    while(ch != 'x')
        printf ("\nEnter the Dividend: ");
        scanf("%d", &dividend);
        printf("\nEnter the Divisor: ");
        scanf("%d", &divisor);

        printf("\n%d / %d: quotient = %d", dividend, divisor, division(dividend, divisor));
        printf("\n%d / %d: remainder = %d", dividend, divisor, remainder);


Preprocessor check if multiple defines are not defined

#if !defined(MANUF) || !defined(SERIAL) || !defined(MODEL)

Add a link to an image in a css style sheet

You can not do that...

via css the URL you put on the background-image is just for the image.

Via HTML you have to add the href for your hyperlink in this way:

<a href="" id="logo">Your logo</a>

With text-indent and some other css you can adjust your a element to show just the image and clicking on it you will go to your link.


I'm here again to show you and explain why my solution is much better:

<a href="" id="logo">Your logo name</a>

This block of HTML is SEO friendly because you have some text inside your link!

How to style it with css:

#logo {
  background-image: url(images/logo.png);
  display: block;
  margin: 0 auto;
  text-indent: -9999px;
  width: 981px;
  height: 180px;

Then if you don't care about SEO good to choose the other answer.

How to completely uninstall Visual Studio 2010?

Download and install IOBIT uninstaller:, find the date in which you install Visual Studio and select all programas from that date r elated to VS. Then run de batch uninstaller. It is not a fully automated solution but it is a lot quicker than going one by one int he add / remove programs in Windows. It even has a power scan to clean the registry.

Disable/turn off inherited CSS3 transitions

Additionally there is a possibility to set a list of properties that will get transitioned by setting the property transition-property: width, height;, more details here

How do I set the path to a DLL file in Visual Studio?

  1. Go to project properties (Alt+F7)
  2. Under Debugging, look to the right
  3. There's an Environment field.
  4. Add your relative path there (relative to vcproj folder) i.e. ..\some-framework\lib by appending PATH=%PATH%;$(ProjectDir)\some-framework\lib or prepending to the path PATH=C:\some-framework\lib;%PATH%
  5. Hit F5 (debug) again and it should work.

Java, How to specify absolute value and square roots

import java.util.Scanner;
class my{
public static void main(String args[])
    Scanner x=new Scanner(;
    double a,b,c=0,d;
    int e,z=0;
    System.out.print("Enter no:");

            while(b*b<=a && z==0)
                    b=b+d;          //*d==0.1 first time*//

        System.out.println("Squre root="+c);


Creating a new dictionary in Python

>>> dict.fromkeys(['a','b','c'],[1,2,3])

{'a': [1, 2, 3], 'b': [1, 2, 3], 'c': [1, 2, 3]}

Task not serializable: when calling function outside closure only on classes not objects

Grega's answer is great in explaining why the original code does not work and two ways to fix the issue. However, this solution is not very flexible; consider the case where your closure includes a method call on a non-Serializable class that you have no control over. You can neither add the Serializable tag to this class nor change the underlying implementation to change the method into a function.

Nilesh presents a great workaround for this, but the solution can be made both more concise and general:

def genMapper[A, B](f: A => B): A => B = {
  val locker = com.twitter.chill.MeatLocker(f)
  x => locker.get.apply(x)

This function-serializer can then be used to automatically wrap closures and method calls:

rdd map genMapper(someFunc)

This technique also has the benefit of not requiring the additional Shark dependencies in order to access KryoSerializationWrapper, since Twitter's Chill is already pulled in by core Spark

<strong> vs. font-weight:bold & <em> vs. font-style:italic

The <em> element - from W3C (HTML5 reference)

YES! There is a clear difference.

The <em> element represents stress emphasis of its contents. The level of emphasis that a particular piece of content has is given by its number of ancestor <em> elements.

<strong>  =  important content
<em>      =  stress emphasis of its contents

The placement of emphasis changes the meaning of the sentence. The element thus forms an integral part of the content. The precise way in which emphasis is used in this way depends on the language.


  1. The <em> element also isnt intended to convey importance; for that purpose, the <strong> element is more appropriate.

  2. The <em> element isn't a generic "italics" element. Sometimes, text is intended to stand out from the rest of the paragraph, as if it was in a different mood or voice. For this, the i element is more appropriate.

Reference (examples): See W3C Reference

How to enable TLS 1.2 support in an Android application (running on Android 4.1 JB)

I have some additions to above mentioned answers Its infact a hack mentioned by Jesse Wilson from okhttp, square here. According to this hack, i had to rename my SSLSocketFactory variable to

private SSLSocketFactory delegate;

This is my TLSSocketFactory class

public class TLSSocketFactory extends SSLSocketFactory {

private SSLSocketFactory delegate;

public TLSSocketFactory() throws KeyManagementException, NoSuchAlgorithmException {
    SSLContext context = SSLContext.getInstance("TLS");
    context.init(null, null, null);
    delegate = context.getSocketFactory();

public String[] getDefaultCipherSuites() {
    return delegate.getDefaultCipherSuites();

public String[] getSupportedCipherSuites() {
    return delegate.getSupportedCipherSuites();

public Socket createSocket() throws IOException {
    return enableTLSOnSocket(delegate.createSocket());

public Socket createSocket(Socket s, String host, int port, boolean autoClose) throws IOException {
    return enableTLSOnSocket(delegate.createSocket(s, host, port, autoClose));

public Socket createSocket(String host, int port) throws IOException, UnknownHostException {
    return enableTLSOnSocket(delegate.createSocket(host, port));

public Socket createSocket(String host, int port, InetAddress localHost, int localPort) throws IOException, UnknownHostException {
    return enableTLSOnSocket(delegate.createSocket(host, port, localHost, localPort));

public Socket createSocket(InetAddress host, int port) throws IOException {
    return enableTLSOnSocket(delegate.createSocket(host, port));

public Socket createSocket(InetAddress address, int port, InetAddress localAddress, int localPort) throws IOException {
    return enableTLSOnSocket(delegate.createSocket(address, port, localAddress, localPort));

private Socket enableTLSOnSocket(Socket socket) {
    if(socket != null && (socket instanceof SSLSocket)) {
        ((SSLSocket)socket).setEnabledProtocols(new String[] {"TLSv1.1", "TLSv1.2"});
    return socket;

and this is how i used it with okhttp and retrofit

 OkHttpClient client=new OkHttpClient();
    try {
        client = new OkHttpClient.Builder()
                .sslSocketFactory(new TLSSocketFactory())
    } catch (KeyManagementException e) {
    } catch (NoSuchAlgorithmException e) {

    Retrofit retrofit = new Retrofit.Builder()

How to highlight a current menu item?

For AngularUI Router users:

<a ui-sref-active="active" ui-sref="app">

And that will place an active class on the object that is selected.

Set View Width Programmatically

in code add below line:

spin27.setLayoutParams(new LinearLayout.LayoutParams(200, 120));

Resizing SVG in html?

Changing the width of the container also fixes it rather than changing the width and height of source file.

.SvgImage img{ width:80%; }

This fixes my issue of re sizing svg . you can give any % based on your requirement.

How can I tell what edition of SQL Server runs on the machine?

select @@version

Sample Output

Microsoft SQL Server 2008 (SP1) - 10.0.2531.0 (X64) Mar 29 2009 10:11:52 Copyright (c) 1988-2008 Microsoft Corporation Developer Edition (64-bit) on Windows NT 6.1 (Build 7600: )

If you just want to get the edition, you can use:

select serverproperty('Edition')

To use in an automated script, you can get the edition ID, which is an integer:

select serverproperty('EditionID')
  • -1253826760 = Desktop
  • -1592396055 = Express
  • -1534726760 = Standard
  • 1333529388 = Workgroup
  • 1804890536 = Enterprise
  • -323382091 = Personal
  • -2117995310 = Developer
  • 610778273 = Enterprise Evaluation
  • 1044790755 = Windows Embedded SQL
  • 4161255391 = Express with Advanced Services

Convert unix time to readable date in pandas dataframe

These appear to be seconds since epoch.

In [20]: df = DataFrame(data['values'])

In [21]: df.columns = ["date","price"]

In [22]: df
<class 'pandas.core.frame.DataFrame'>
Int64Index: 358 entries, 0 to 357
Data columns (total 2 columns):
date     358  non-null values
price    358  non-null values
dtypes: float64(1), int64(1)

In [23]: df.head()
         date  price
0  1349720105  12.08
1  1349806505  12.35
2  1349892905  12.15
3  1349979305  12.19
4  1350065705  12.15
In [25]: df['date'] = pd.to_datetime(df['date'],unit='s')

In [26]: df.head()
                 date  price
0 2012-10-08 18:15:05  12.08
1 2012-10-09 18:15:05  12.35
2 2012-10-10 18:15:05  12.15
3 2012-10-11 18:15:05  12.19
4 2012-10-12 18:15:05  12.15

In [27]: df.dtypes
date     datetime64[ns]
price           float64
dtype: object

Could not load file or assembly 'Newtonsoft.Json' or one of its dependencies. Manifest definition does not match the assembly reference

After hours struggling with this... I did the following:



  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">

      <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
      <bindingRedirect oldVersion="" newVersion="" />

    <!-- other assemblies... -->


The key to enter the correct newVersion and oldVersion number is open the project's References find the package go to its properties or click alt + enter

You'll find a section Version which in my case was while its actually 12.0.3 when exploring with Manage NuGet.

So you need to pick the package's version from the reference properties (in my case

Finally, clean and rebuild the project (you might want to delete the bin and obj folders before).

You might face other packages dependencies issues, i did that for all and they worked.

Hibernate throws MultipleBagFetchException - cannot simultaneously fetch multiple bags

When you have too complex objects with saveral collection could not be good idea to have all of them with EAGER fetchType, better use LAZY and when you really need to load the collections use: Hibernate.initialize(parent.child) to fetch the data.

In Subversion can I be a user other than my login name?

"svn co --username=yourUserName --password=yourpassword http://path-to-your-svn"

Worked for me when on another user account. You will be prompted to enter username/password again though. You need to login like the above once and you are all set for the subsequent times(Unless you restart your machine).

AngularJS - Any way for $ to send request parameters instead of JSON?

This might be a bit of a hack, but I avoided the issue and converted the json into PHP's POST array on the server side:

$_POST = json_decode(file_get_contents('php://input'), true);

Finish an activity from another activity

See my answer to Stack Overflow question Finish All previous activities.

What you need is to add the Intent.FLAG_CLEAR_TOP. This flag makes sure that all activities above the targeted activity in the stack are finished and that one is shown.

Another thing that you need is the SINGLE_TOP flag. With this one you prevent Android from creating a new activity if there is one already created in the stack.

Just be wary that if the activity was already created, the intent with these flags will be delivered in the method called onNewIntent(intent) (you need to overload it to handle it) in the target activity.

Then in onNewIntent you have a method called restart or something that will call finish() and launch a new intent toward itself, or have a repopulate() method that will set the new data. I prefer the second approach, it is less expensive and you can always extract the onCreate logic into a separate method that you can call for populate.

Directly assigning values to C Pointers

First Program with comments

#include <stdio.h>

int main(){
    int *ptr;             //Create a pointer that points to random memory address

    *ptr = 20;            //Dereference that pointer, 
                          // and assign a value to random memory address.
                          //Depending on external (not inside your program) state
                          // this will either crash or SILENTLY CORRUPT another 
                          // data structure in your program.  

    printf("%d", *ptr);   //Print contents of same random memory address
                          // May or may not crash, depending on who owns this address

    return 0;             

Second Program with comments

#include <stdio.h>

int main(){
    int *ptr;              //Create pointer to random memory address

    int q = 50;            //Create local variable with contents int 50

    ptr = &q;              //Update address targeted by above created pointer to point
                           // to local variable your program properly created

    printf("%d", *ptr);    //Happily print the contents of said local variable (q)
    return 0;

The key is you cannot use a pointer until you know it is assigned to an address that you yourself have managed, either by pointing it at another variable you created or to the result of a malloc call.

Using it before is creating code that depends on uninitialized memory which will at best crash but at worst work sometimes, because the random memory address happens to be inside the memory space your program already owns. God help you if it overwrites a data structure you are using elsewhere in your program.

Notification Icon with the new Firebase Cloud Messaging system

atm they are working on that issue

when you send a notification from the Firebase console is uses your app icon by default, and the Android system will turn that icon solid white when in the notification bar.

If you are unhappy with that result you should implement FirebaseMessagingService and create the notifications manually when you receive a message. We are working on a way to improve this but for now that's the only way.

edit: with SDK 9.8.0 add to AndroidManifest.xml

<meta-data android:name="" android:resource="@drawable/my_favorite_pic"/>

Figure out size of UILabel based on String in Swift

@IBOutlet weak var constraintTxtV: NSLayoutConstraint!
func TextViewDynamicallyIncreaseSize() {
    let contentSize = self.txtVDetails.sizeThatFits(self.txtVDetails.bounds.size)
    let higntcons = contentSize.height
    constraintTxtV.constant = higntcons

Int division: Why is the result of 1/3 == 0?

Do "double g=1.0/3.0;" instead.

Can not change UILabel text color

Add attributed text color in swift code.

Swift 4:

  let greenColor = UIColor(red: 10/255, green: 190/255, blue: 50/255, alpha: 1)
  let attributedStringColor = [NSAttributedStringKey.foregroundColor : greenColor];

  let attributedString = NSAttributedString(string: "Hello World!", attributes: attributedStringColor)
  label.attributedText = attributedString

for Swift 3:

  let greenColor = UIColor(red: 10/255, green: 190/255, blue: 50/255, alpha: 1)
  let attributedStringColor : NSDictionary = [NSForegroundColorAttributeName : greenColor];

  let attributedString = NSAttributedString(string: "Hello World!", attributes: attributedStringColor as? [String : AnyObject])
  label.attributedText = attributedString 

Unzipping files in Python

zipfile is a somewhat low-level library. Unless you need the specifics that it provides, you can get away with shutil's higher-level functions make_archive and unpack_archive.

make_archive is already described in this answer. As for unpack_archive:

import shutil
shutil.unpack_archive(filename, extract_dir)

unpack_archive detects the compression format automatically from the "extension" of filename (.zip, .tar.gz, etc), and so does make_archive. Also, filename and extract_dir can be any path-like objects (e.g. pathlib.Path instances) since Python 3.7.

Display unescaped HTML in Vue.js

Starting with Vue2, the triple braces were deprecated, you are to use v-html.

<div v-html="task.html_content"> </div>

It is unclear from the documentation link as to what we are supposed to place inside v-html, your variables goes inside v-html.

Also, v-html works only with <div> or <span> but not with <template>.

If you want to see this live in an app, click here.

crop text too long inside div

<div class="crop">longlong longlong longlong longlong longlong longlong </div>?

This is one possible approach i can think of

.crop {width:100px;overflow:hidden;height:50px;line-height:50px;}?

This way the long text will still wrap but will not be visible due to overflow set, and by setting line-height same as height we are making sure only one line will ever be displayed.

See demo here and nice overflow property description with interactive examples.

lexers vs parsers

Yes, they are very different in theory, and in implementation.

Lexers are used to recognize "words" that make up language elements, because the structure of such words is generally simple. Regular expressions are extremely good at handling this simpler structure, and there are very high-performance regular-expression matching engines used to implement lexers.

Parsers are used to recognize "structure" of a language phrases. Such structure is generally far beyond what "regular expressions" can recognize, so one needs "context sensitive" parsers to extract such structure. Context-sensitive parsers are hard to build, so the engineering compromise is to use "context-free" grammars and add hacks to the parsers ("symbol tables", etc.) to handle the context-sensitive part.

Neither lexing nor parsing technology is likely to go away soon.

They may be unified by deciding to use "parsing" technology to recognize "words", as is currently explored by so-called scannerless GLR parsers. That has a runtime cost, as you are applying more general machinery to what is often a problem that doesn't need it, and usually you pay for that in overhead. Where you have lots of free cycles, that overhead may not matter. If you process a lot of text, then the overhead does matter and classical regular expression parsers will continue to be used.

The network adapter could not establish the connection - Oracle 11g

First check your listener is on or off. Go to net manager then Local -> service naming -> orcl. Then change your HOST NAME and put your PC name. Now go to LISTENER and change the HOST and put your PC name.

How should I use try-with-resources with JDBC?

I realize this was long ago answered but want to suggest an additional approach that avoids the nested try-with-resources double block.

public List<User> getUser(int userId) {
    try (Connection con = DriverManager.getConnection(myConnectionURL);
         PreparedStatement ps = createPreparedStatement(con, userId); 
         ResultSet rs = ps.executeQuery()) {

         // process the resultset here, all resources will be cleaned up

    } catch (SQLException e) {

private PreparedStatement createPreparedStatement(Connection con, int userId) throws SQLException {
    String sql = "SELECT id, username FROM users WHERE id = ?";
    PreparedStatement ps = con.prepareStatement(sql);
    ps.setInt(1, userId);
    return ps;

Get fragment (value after hash '#') from a URL in php

If you want to get the value after the hash mark or anchor as shown in a user's browser: This isn't possible with "standard" HTTP as this value is never sent to the server (hence it won't be available in $_SERVER["REQUEST_URI"] or similar predefined variables). You would need some sort of JavaScript magic on the client side, e.g. to include this value as a POST parameter.

If it's only about parsing a known URL from whatever source, the answer by mck89 is perfectly fine though.

git pull remote branch cannot find remote ref

For me, it was because I was trying to pull a branch which was already deleted from Github.

CASE (Contains) rather than equal statement

Pseudo code, something like:

  When CHARINDEX('lactulose', dbo.Table.Column) > 0 Then 'BP Medication'
END AS 'Medication Type'

This does not care where the keyword is found in the list and avoids depending on formatting of spaces and commas.

Sorting Values of Set

You're using the default comparator to sort a Set<String>. In this case, that means lexicographic order. Lexicographically, "12" comes before "15", comes before "5".

Either use a Set<Integer>:

Set<Integer> set=new HashSet<Integer>();

Or use a different comparator:

Collections.sort(list, new Comparator<String>() {
    public int compare(String a, String b) {
        return Integer.parseInt(a) - Integer.parseInt(b);

How to write lists inside a markdown table?

Yes, you can merge them using HTML. When I create tables in .md files from Github, I always like to use HTML code instead of markdown.

Github Flavored Markdown supports basic HTML in .md file. So this would be the answer:

Markdown mixed with HTML:

| Tables        | Are           | Cool  |
| ------------- |:-------------:| -----:|
| col 3 is      | right-aligned | $1600 |
| col 2 is      | centered      |   $12 |
| zebra stripes | are neat      |    $1 |
| <ul><li>item1</li><li>item2</li></ul>| See the list | from the first column|

Or pure HTML:

      <th align="center">Are</th>
      <th align="right">Cool</th>
      <td>col 3 is</td>
      <td align="center">right-aligned</td>
      <td align="right">$1600</td>
      <td>col 2 is</td>
      <td align="center">centered</td>
      <td align="right">$12</td>
      <td>zebra stripes</td>
      <td align="center">are neat</td>
      <td align="right">$1</td>
      <td align="center">See the list</td>
      <td align="right">from the first column</td>

This is how it looks on Github:

Is it possible to create static classes in PHP (like in C#)?

You can have static classes in PHP but they don't call the constructor automatically (if you try and call self::__construct() you'll get an error).

Therefore you'd have to create an initialize() function and call it in each method:


class Hello
    private static $greeting = 'Hello';
    private static $initialized = false;

    private static function initialize()
        if (self::$initialized)

        self::$greeting .= ' There!';
        self::$initialized = true;

    public static function greet()
        echo self::$greeting;

Hello::greet(); // Hello There!


How can I send a file document to the printer and have it print?

I know Edwin answered it above but his only prints one document. I use this code to print all files from a given directory.

public void PrintAllFiles()
    System.Diagnostics.ProcessStartInfo info = new System.Diagnostics.ProcessStartInfo();
    info.Verb = "print";
    System.Diagnostics.Process p = new System.Diagnostics.Process();
    //Load Files in Selected Folder
    string[] allFiles = System.IO.Directory.GetFiles(Directory);
    foreach (string file in allFiles)
        info.FileName = @file;
        info.CreateNoWindow = true;
        info.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
         p.StartInfo = info;
    //p.Kill(); Can Create A Kill Statement Here... but I found I don't need one
    MessageBox.Show("Print Complete");

It essentually cycles through each file in the given directory variable Directory - > for me it was @"C:\Users\Owner\Documents\SalesVaultTesting\" and prints off those files to your default printer.

Regular expression to match any character being repeated more than 10 times

The regex you need is /(.)\1{9,}/.


use warnings;
use strict;
my $regex = qr/(.)\1{9,}/;
print "NO" if "abcdefghijklmno" =~ $regex;
print "YES" if "------------------------" =~ $regex;
print "YES" if "========================" =~ $regex;

Here the \1 is called a backreference. It references what is captured by the dot . between the brackets (.) and then the {9,} asks for nine or more of the same character. Thus this matches ten or more of any single character.

Although the above test script is in Perl, this is very standard regex syntax and should work in any language. In some variants you might need to use more backslashes, e.g. Emacs would make you write \(.\)\1\{9,\} here.

If a whole string should consist of 9 or more identical characters, add anchors around the pattern:

my $regex = qr/^(.)\1{9,}$/;

Read .doc file with python

One can use the textract library. It take care of both "doc" as well as "docx"

import textract
text = textract.process("path/to/file.extension")

You can even use 'antiword' (sudo apt-get install antiword) and then convert doc to first into docx and then read through docx2txt.

antiword filename.doc > filename.docx

Ultimately, textract in the backend is using antiword.

How to repeat a char using printf?

you can make a function that do this job and use it

#include <stdio.h>

void repeat (char input , int count )
    for (int i=0; i != count; i++ )
        printf("%c", input);

int main()
    repeat ('#', 5);
    return 0;

This will output


The name 'ConfigurationManager' does not exist in the current context

Adding this answer, as none of the suggested solutions works for me.

  1. Right-click on references tab to add reference.
  2. Click on Assemblies tab
  3. Search for 'System.Configuration'
  4. Click OK.

"Sub or Function not defined" when trying to run a VBA script in Outlook

I think you need to update your libraries so that your VBA code works, your using ms outlook

Does a VPN Hide my Location on Android?

Your question can be conveniently divided into several parts:

Does a VPN hide location? Yes, he is capable of this. This is not about GPS determining your location. If you try to change the region via VPN in an application that requires GPS access, nothing will work. However, sites define your region differently. They get an IP address and see what country or region it belongs to. If you can change your IP address, you can change your region. This is exactly what VPNs can do.

How to hide location on Android? There is nothing difficult in figuring out how to set up a VPN on Android, but a couple of nuances still need to be highlighted. Let's start with the fact that not all Android VPNs are created equal. For example, VeePN outperforms many other services in terms of efficiency in circumventing restrictions. It has 2500+ VPN servers and a powerful IP and DNS leak protection system.

You can easily change the location of your Android device by using a VPN. Follow these steps for any device model (Samsung, Sony, Huawei, etc.):

  1. Download and install a trusted VPN.

  2. Install the VPN on your Android device.

  3. Open the application and connect to a server in a different country.

  4. Your Android location will now be successfully changed!

Is it legal? Yes, changing your location on Android is legal. Likewise, you can change VPN settings in Microsoft Edge on your PC, and all this is within the law. VPN allows you to change your IP address, safeguarding your privacy and protecting your actual location from being exposed. However, VPN laws may vary from country to country. There are restrictions in some regions.

Brief summary: Yes, you can change your region on Android and a VPN is a necessary assistant for this. It's simple, safe and legal. Today, VPN is the best way to change the region and unblock sites with regional restrictions.

MVC which submit button has been pressed

In Core 2.2 Razor pages this syntax works:

    <button type="submit" name="Submit">Save</button>
    <button type="submit" name="Cancel">Cancel</button>
public async Task<IActionResult> OnPostAsync()
    if (!ModelState.IsValid)
        return Page();
    var sub = Request.Form["Submit"];
    var can = Request.Form["Cancel"];
    if (sub.Count > 0)

jQuery posting valid json in request body

An actual JSON request would look like this:

data: '{"command":"on"}',

Where you're sending an actual JSON string. For a more general solution, use JSON.stringify() to serialize an object to JSON, like this:

data: JSON.stringify({ "command": "on" }),

To support older browsers that don't have the JSON object, use json2.js which will add it in.

What's currently happening is since you have processData: false, it's basically sending this: ({"command":"on"}).toString() which is [object Object]...what you see in your request.

How to Generate Unique Public and Private Key via RSA

When you use a code like this:

using (var rsa = new RSACryptoServiceProvider(1024))
   // Do something with the key...
   // Encrypt, export, etc.

.NET (actually Windows) stores your key in a persistent key container forever. The container is randomly generated by .NET

This means:

  1. Any random RSA/DSA key you have EVER generated for the purpose of protecting data, creating custom X.509 certificate, etc. may have been exposed without your awareness in the Windows file system. Accessible by anyone who has access to your account.

  2. Your disk is being slowly filled with data. Normally not a big concern but it depends on your application (e.g. it might generates hundreds of keys every minute).

To resolve these issues:

using (var rsa = new RSACryptoServiceProvider(1024))
      // Do something with the key...
      // Encrypt, export, etc.
      rsa.PersistKeyInCsp = false;


How to set tint for an image view programmatically in android?

After i tried all methods and they did not work for me.

I get the solution by using another PortDuff.MODE.


How to convert entire dataframe to numeric while preserving decimals?

You might need to do some checking. You cannot safely convert factors directly to numeric. as.character must be applied first. Otherwise, the factors will be converted to their numeric storage values. I would check each column with is.factor then coerce to numeric as necessary.

df1[] <- lapply(df1, function(x) {
    if(is.factor(x)) as.numeric(as.character(x)) else x
sapply(df1, class)
#         a         b 
# "numeric" "numeric" 

Why do we need to install gulp globally and locally?

Just because I haven't seen it here, if you are on MacOS or Linux, I suggest you add this to your PATH (in your bashrc etc):


With this relative path entry, if you are sitting in the root folder of any node project, you can run any command line tool (eslint, gulp, etc. etc.) without worrying about "global installs" or npm run etc.

Once I did this, I've never installed a module globally.

How to upload images into MySQL database using PHP code

Firstly, you should check if your image column is BLOB type!

I don't know anything about your SQL table, but if I'll try to make my own as an example.

We got fields id (int), image (blob) and image_name (varchar(64)).

So the code should look like this (assume ID is always '1' and let's use this mysql_query):

$image = addslashes(file_get_contents($_FILES['image']['tmp_name'])); //SQL Injection defence!
$image_name = addslashes($_FILES['image']['name']);
$sql = "INSERT INTO `product_images` (`id`, `image`, `image_name`) VALUES ('1', '{$image}', '{$image_name}')";
if (!mysql_query($sql)) { // Error handling
    echo "Something went wrong! :("; 

You are doing it wrong in many ways. Don't use mysql functions - they are deprecated! Use PDO or MySQLi. You should also think about storing files locations on disk. Using MySQL for storing images is thought to be Bad Idea™. Handling SQL table with big data like images can be problematic.

Also your HTML form is out of standards. It should look like this:

<form action="insert_product.php" method="POST" enctype="multipart/form-data">
    <label>File: </label><input type="file" name="image" />
    <input type="submit" />


When dealing with files and storing them as a BLOB, the data must be escaped using mysql_real_escape_string(), otherwise it will result in a syntax error.

Convert Variable Name to String?

I think this is a cool solution and I suppose the best you can get. But do you see any way to handle the ambigious results, your function may return? As "is" operator behaves unexpectedly with integers shows, low integers and strings of the same value get cached by python so that your variablename-function might priovide ambigous results with a high probability. In my case, I would like to create a decorator, that adds a new variable to a class by the varialbename i pass it:

def inject(klass, dependency):

But if your method returns ambigous results, how can I know the name of the variable I added?

var any_var="myvarcontent"
var myvar="myvarcontent"
class myclasss():
    def myclass_method(self):
        print self.__myvar    #I can not be sure, that this variable will be set...

Maybe if I will also check the local list I could at least remove the "dependency"-Variable from the list, but this will not be a reliable result.

jQuery if Element has an ID?

Simply use:

$(".parent a[id]");

Any way to return PHP `json_encode` with encode UTF-8 and not Unicode?

Use JSON_UNESCAPED_UNICODE inside json_encode() if your php version >=5.4.

cast or convert a float to nvarchar?

Float won't convert into NVARCHAR directly, first we need to convert float into money datatype and then convert into NVARCHAR, see the examples below.









In Example2 value is converted into float to NVARCHAR

How to upgrade pip3?

If you have 2 versions of Python (eg: 2.7.x and 3.6), you need do:

  1. add the path of 2.x to system PATH
  2. add the path of 3.x to system PATH
  3. pip3 install --upgrade pip setuptools wheel

for example, in my .zshrc file:

export PATH=/usr/local/Cellar/python@2/2.7.15/bin:/usr/local/Cellar/python/3.6.5/bin:$PATH

You can exec command pip --version and pip3 --version check the pip from the special version. Because if don't add Python path to $PATH, and exec pip3 install --upgrade pip setuptools wheel, your pip will be changed to pip from python3, but the pip should from python2.x