Programs & Examples On #Dynamic linking

Dynamic linking is a system which allows libraries to remain separate from programs until loaded, contrast static linking.

Static linking vs dynamic linking

static linking gives you only a single exe, inorder to make a change you need to recompile your whole program. Whereas in dynamic linking you need to make change only to the dll and when you run your exe, the changes would be picked up at runtime.Its easier to provide updates and bug fixes by dynamic linking (eg: windows).

Telling gcc directly to link a library statically

You can add .a file in the linking command:

  gcc yourfiles /path/to/library/libLIBRARY.a

But this is not talking with gcc driver, but with ld linker as options like -Wl,anything are.

When you tell gcc or ld -Ldir -lLIBRARY, linker will check both static and dynamic versions of library (you can see a process with -Wl,--verbose). To change order of library types checked you can use -Wl,-Bstatic and -Wl,-Bdynamic. Here is a man page of gnu LD:

To link your program with lib1, lib3 dynamically and lib2 statically, use such gcc call:

gcc program.o -llib1 -Wl,-Bstatic -llib2 -Wl,-Bdynamic -llib3

Assuming that default setting of ld is to use dynamic libraries (it is on Linux).

When to use dynamic vs. static libraries

We use a lot of DLL's (> 100) in our project. These DLL's have dependencies on each other and therefore we chose the setup of dynamic linking. However it has the following disadvantages:

  • slow startup (> 10 seconds)
  • DLL's had to be versioned, since windows loads modules on uniqueness of names. Own written components would otherwise get the wrong version of the DLL (i.e. the one already loaded instead of its own distributed set)
  • optimizer can only optimize within DLL boundaries. For example the optimizer tries to place frequently used data and code next to each other, but this will not work across DLL boundaries

Maybe a better setup was to make everything a static library (and therefore you just have one executable). This works only if no code duplication takes place. A test seems to support this assumption, but i couldn't find an official MSDN quote. So for example make 1 exe with:

  • exe uses shared_lib1, shared_lib2
  • shared_lib1 use shared_lib2
  • shared_lib2

The code and variables of shared_lib2 should be present in the final merged executable only once. Can anyone support this question?

jQuery override default validation error message display (Css) Popup/Tooltip like

A few things:

First, I don't think you really need a validation error for a radio fieldset because you could just have one of the fields checked by default. Most people would rather correct something then provide something. For instance:

   Age: (*) 12 - 18 | () 19 - 30 | 31 - 50 

is more likely to be changed to the right answer as the person DOESN'T want it to go to the default. If they see it blank, they are more likely to think "none of your business" and skip it.

Second, I was able to get the effect I think you are wanting without any positioning properties. You just add padding-right to the form (or the div of the form, whatever) to provide enough room for your error and make sure your error will fit in that area. Then, you have a pre-set up css class called "error" and you set it as having a negative margin-top roughly the height of your input field and a margin-left about the distance from the left to where your padding-right should start. I tried this out, it's not great, but it works with three properties and requires no floats or absolutes:

   <style type="text/css">
    .error {
        width: 13em; /* Ensures that the div won't exceed right padding of form */
        margin-top: -1.5em;  /*Moves the div up to the same level as input */
        margin-left: 11em;   /*Moves div to the right */
        font-size: .9em;     /*Makes sure that the error div is smaller than input */

   <label for="name">Name:</label><input id="name" type="textbox" />
   <div class="error"><<< This field is required!</div>
   <label for="numb">Phone:</label><input id="numb" type="textbox" />
   <div class="error"><<< This field is required!</div>

Matrix multiplication using arrays

The method mults is a procedure(Pascal) or subroutine(Fortran)

The method multMatrix is a function(Pascal,Fortran)

import java.util.*;

public class MatmultE
private static Scanner sc = new Scanner(;
  public static void main(String [] args)
    double[][] A={{4.00,3.00},{2.00,1.00}}; 
    double[][] B={{-0.500,1.500},{1.000,-2.0000}};
    double[][] C=multMatrix(A,B);

    double a[][] = {{1, 2, -2, 0}, {-3, 4, 7, 2}, {6, 0, 3, 1}};
    double b[][] = {{-1, 3}, {0, 9}, {1, -11}, {4, -5}};
    double[][] c=multMatrix(a,b);

    double[][] a1 = readMatrix();
    double[][] b1 = readMatrix();
    double[][] c1 = new double[a1.length][b1[0].length];

   public static double[][] readMatrix() {
       int rows = sc.nextInt();
       int cols = sc.nextInt();
       double[][] result = new double[rows][cols];
       for (int i = 0; i < rows; i++) {
           for (int j = 0; j < cols; j++) {
              result[i][j] = sc.nextDouble();
       return result;

  public static void printMatrix(double[][] mat) {
       int rows = mat.length;
       int columns = mat[0].length;
       for (int i = 0; i < rows; i++) {
           for (int j = 0; j < columns; j++) {
               System.out.printf("%8.3f " , mat[i][j]);

  public static void printMatrixE(double[][] mat) {
       int rows = mat.length;
       int columns = mat[0].length;
       for (int i = 0; i < rows; i++) {
           for (int j = 0; j < columns; j++) {
               System.out.printf("%9.2e " , mat[i][j]);

   public static double[][] multMatrix(double a[][], double b[][]){//a[m][n], b[n][p]
   if(a.length == 0) return new double[0][0];
   if(a[0].length != b.length) return null; //invalid dims

   int n = a[0].length;
   int m = a.length;
   int p = b[0].length;

   double ans[][] = new double[m][p];

   for(int i = 0;i < m;i++){
      for(int j = 0;j < p;j++){
         for(int k = 0;k < n;k++){
            ans[i][j] += a[i][k] * b[k][j];
   return ans;

   public static void mults(double a[][], double b[][], double c[][], int r1, 
                        int c1, int r2, int c2){
      for(int i = 0;i < r1;i++){
         for(int j = 0;j < c2;j++){
            for(int k = 0;k < c1;k++){
               c[i][j] += a[i][k] * b[k][j];

where as input matrix you can enter


4 4
1 1 1 1
2 4 8 16
3 9 27 81
4 16 64 256
4 3
4.0 -3.0 4.0
-13.0 19.0 -7.0
3.0 -2.0 7.0
-1.0 1.0 -1.0

in unix like cmmd line execute the command:

$ java MatmultE < inE.txt > outE.txt

and you get the output


   4.000    3.000 
   2.000    1.000 

  -0.500    1.500 
   1.000   -2.000 

   1.000    0.000 
   0.000    1.000 

   1.000    2.000   -2.000    0.000 
  -3.000    4.000    7.000    2.000 
   6.000    0.000    3.000    1.000 

  -1.000    3.000 
   0.000    9.000 
   1.000  -11.000 
   4.000   -5.000 

  -3.000   43.000 
  18.000  -60.000 
   1.000  -20.000 

  -7.000   15.000    3.000 
 -36.000   70.000   20.000 
-105.000  189.000   57.000 
-256.000  420.000   96.000 

-7.00e+00  1.50e+01  3.00e+00 
-3.60e+01  7.00e+01  2.00e+01 
-1.05e+02  1.89e+02  5.70e+01 
-2.56e+02  4.20e+02  9.60e+01 

How do you determine the ideal buffer size when using FileInputStream?

As already mentioned in other answers, use BufferedInputStreams.

After that, I guess the buffer size does not really matter. Either the program is I/O bound, and growing buffer size over BIS default, will not make any big impact on performance.

Or the program is CPU bound inside the MessageDigest.update(), and majority of the time is not spent in the application code, so tweaking it will not help.

(Hmm... with multiple cores, threads might help.)

Getting number of days in a month

You want DateTime.DaysInMonth:

int days = DateTime.DaysInMonth(year, month);

Obviously it varies by year, as sometimes February has 28 days and sometimes 29. You could always pick a particular year (leap or not) if you want to "fix" it to one value or other.

Breaking out of a for loop in Java

You can use:

for (int x = 0; x < 10; x++) {
  if (x == 5) { // If x is 5, then break it.

Referencing value in a closed Excel workbook using INDIRECT?

If you know the number of sheet you want to reference you can use below function to find out the name. Than you can use it in INDIRECT funcion.

Public Function GETSHEETNAME(address As String, Optional SheetNumber As Integer = 1) As String

    Set WS = GetObject(address).Worksheets
    GETSHEETNAME = WS(SheetNumber).Name

End Function

This solution doesn't require referenced workbook to be open - Excel gonna open it by itself (but it's gonna be hidden).

Java Command line arguments

Every Java program starts with

public static void main(String[] args) {

That array of type String that main() takes as a parameter holds the command line arguments to your program. If the user runs your program as

$ java myProgram a

then args[0] will hold the String "a".

Default visibility for C# classes and members (fields, methods, etc.)?

By default, the access modifier for a class is internal. That means to say, a class is accessible within the same assembly. But if we want the class to be accessed from other assemblies then it has to be made public.

Implement paging (skip / take) functionality with this query

SQL 2008

Radim Köhler's answer works, but here is a shorter version:

select top 20 * from
select *,
from tablename
) x
where ROW_NUM>10


Windows task scheduler error 101 launch failure code 2147943785

Had the same issue today. I added the user to:

Administrative Tools -> Local Security Policy -> Local Policies -> User Rights Assignment -> Log on as a batch job

But was still getting the error. I found this post, and it turns out there's also this setting that I had to remove the user from (not sure how it got in there):

Administrative Tools -> Local Security Policy -> Local Policies -> User Rights Assignment -> Deny log on as a batch job

So just be aware that you may need to check both policies for the user.

Pod install is staying on "Setting up CocoaPods Master repo"

Cocoa pods - reduce wait times to 10% ( on Mac OS ) :

1- type pod setup in your project folder ( first you have to be in the project folder) from terminal in Mac OS.

2- CTRL+z to stop after it creates master directory ( folder ) [you can see it in your cocoa pods folder location : ~/.cocoapods/repos]

  1. Download .zip from

     master branch ( its 301 MB) , Extract it . It will take approx 5-10 mins

4.Copy the content to ~/.cocoapods/repos ( now here you only need to copy the contents inside the master folder , so make sure that master folder is created already with pod setup command )

5- once you copy it ( or I should say move , drag and drop as copying will take forever , as its very large ), you can then do pod install --no-repo-update 6- your pods in the pod file now will start installing Here is a screenshot enter image description here

Scroll part of content in fixed position container

Actually this is better way to do that. If height: 100% is used, the content goes off the border, but when it is 95% everything is in order:

div#scrollable {
    overflow-y: scroll;
    height: 95%;

How to add class active on specific li on user click with jQuery

You specified both jQuery and Javascript in the tags so here's both approaches.


var selector = '.nav li';

$(selector).on('click', function(){


Pure Javascript:

var selector, elems, makeActive;

selector = '.nav li';

elems = document.querySelectorAll(selector);

makeActive = function () {
    for (var i = 0; i < elems.length; i++)


for (var i = 0; i < elems.length; i++)
    elems[i].addEventListener('mousedown', makeActive);


jQuery with event delegation:

Please note that in approach 1, the handler is directly bound to that element. If you're expecting the DOM to update and new lis to be injected, it's better to use event delegation and delegate to the next element that will remain static, in this case the .nav:

$('.nav').on('click', 'li', function(){
    $('.nav li').removeClass('active');


The subtle difference is that the handler is bound to the .nav now, so when you click the li the event bubbles up the DOM to the .nav which invokes the handler if the element clicked matches your selector argument. This means new elements won't need a new handler bound to them, because it's already bound to an ancestor.

It's really quite interesting. Read more about it here:

How do you fix a bad merge, and replay your good commits onto a fixed merge?

This is the best way:

Just be sure to backup the copies of the files first.


The edit by Neon got unfortunately rejected during review.
See Neons post below, it might contain useful information!

E.g. to remove all *.gz files accidentally committed into git repository:

$ du -sh .git ==> e.g. 100M
$ git filter-branch --index-filter 'git rm --cached --ignore-unmatch *.gz' HEAD
$ git push origin master --force
$ rm -rf .git/refs/original/
$ git reflog expire --expire=now --all
$ git gc --prune=now
$ git gc --aggressive --prune=now

That still didn't work for me? (I am currently at git version

$ du -sh .git ==> e.g. 100M

Not sure why, since I only had ONE master branch. Anyways, I finally got my git repo truely cleaned up by pushing into a new empty and bare git repository, e.g.

$ git init --bare /path/to/newcleanrepo.git
$ git push /path/to/newcleanrepo.git master
$ du -sh /path/to/newcleanrepo.git ==> e.g. 5M 


Then I clone that to a new directory and moved over it's .git folder into this one. e.g.

$ mv .git ../large_dot_git
$ git clone /path/to/newcleanrepo.git ../tmpdir
$ mv ../tmpdir/.git .
$ du -sh .git ==> e.g. 5M 

(yeah! finally cleaned up!)

After verifying that all is well, then you can delete the ../large_dot_git and ../tmpdir directories (maybe in a couple weeks or month from now, just in case...)

PHP: Read Specific Line From File

Use stream_get_line: stream_get_line — Gets line from stream resource up to a given delimiter Source:

How to use custom font in a project written in Android Studio

You can use easy & simple EasyFonts third party library to set variety of custom font to your TextView. By using this library you should not have to worry about downloading and adding fonts into the assets/fonts folder. Also about Typeface object creation. You will be free from creating asset folder too.


TextView myTextView = (TextView)findViewById(;

There are many type of fonts provided by this library.

oracle plsql: how to parse XML and insert into table

select *  
FROM XMLTABLE('/person/row'  
                           <City>Los angeles</City>
                           <City>Los angeles</City>
            --describe columns and path to them:  
            name  varchar2(20)    PATH './name',  
            state varchar2(20)    PATH './Address/State',  
            city  varchar2(20)    PATH './Address/City'
     ) xmlt  

"unexpected token import" in Nodejs5 and babel?

Involve following steps to resolve the issue:

1) Install the CLI and env preset

$ npm install --save-dev babel-cli babel-preset-env

2) Create a .babelrc file

  "presets": ["env"]

3) configure npm start in package.json

"scripts": {
    "start": "babel-node ./server/app.js",
    "test": "echo \"Error: no test specified\" && exit 1"

4) then start app

$ npm start


Just remove old APK android/app/build/outputs/apk/debug/app-debug.apk in the folder. that's all. enjoy your coding...

In Eclipse, what can cause Package Explorer "red-x" error-icon when all Java sources compile without errors?

I want to start by thanking everyone that answered. But cleaning and rebuilding was not enough in my case because the problem was still there and needed fixing.

Turned out that one of my package directories had accidentally been copied so that an extra directory now existed called "Copy of dagskra" containing Java files with wrong package declarations. In addition the errors in this "new" directory don't show up with a "red-x" in the package that it exists in:

Snapshot from Package Explorer showing errorous "Copy of dagskra" directoryr

It was the hint of reading the "Problems" tab :-) that turned me into the right direction, so I'm selecting that answer as the accepted answer because this is what I needed:

Snapshot from Problems tab

Hoping this will help others...

SameSite warning Chrome 77

If you are testing on localhost and you have no control of the response headers, you can disable it with a chrome flag.

Visit the url and disable it: chrome://flags/#same-site-by-default-cookies SameSite by default cookies screenshot

I need to disable it because Chrome Canary just started enforcing this rule as of approximately V 82.0.4078.2 and now it's not setting these cookies.

Note: I only turn this flag on in Chrome Canary that I use for development. It's best not to turn the flag on for everyday Chrome browsing for the same reasons that google is introducing it.

Windows 8.1 gets Error 720 on connect VPN

First I would like to thank Rose who was willing to help us, but your answer could solve the problem on a computer, but in others there was what was done could not always connect gets error 720. After much searching and contact the Microsoft support we can solve. In Device Manager, on the View menu, select to show hidden devices. Made it look for a remote Miniport IP or network monitor that is with warning of problems with the driver icon. In its properties in the details tab check the Key property of the driver. Look for this key in Regedit on Local Machine, make a backup of that key and delete it. Restart your windows. Reopen your device manager and select the miniport that had deleted the record. Activate the option to update the driver and look for the option driver on the computer manually and then use the option to locate the driver from the list available on the computer on the next screen uncheck show compatible hardware. Then you must select the Microsoft Vendor and the driver WAN Miniport the type that is changing, IP or IPV6 L2TP Network Monitor. After upgrading restart the computer.

I know it's a bit laborious but that was the only way that worked on all computers.

SQL Server - Create a copy of a database table and place it in the same database?

1st option

select *
  into ABC_1
  from ABC;

2nd option: use SSIS, that is right click on database in object explorer > all tasks > export data

  • source and target: your DB
  • source table: ABC
  • target table: ABC_1 (table will be created)

Sass and combined child selector

Without the combined child selector you would probably do something similar to this:

foo {
  bar {
    baz {
      color: red;

If you want to reproduce the same syntax with >, you could to this:

foo {
  > bar {
    > baz {
      color: red;

This compiles to this:

foo > bar > baz {
  color: red;

Or in sass:

  > bar
    > baz
      color: red

What are .a and .so files?

Archive libraries (.a) are statically linked i.e when you compile your program with -c option in gcc. So, if there's any change in library, you need to compile and build your code again.

The advantage of .so (shared object) over .a library is that they are linked during the runtime i.e. after creation of your .o file -o option in gcc. So, if there's any change in .so file, you don't need to recompile your main program. But make sure that your main program is linked to the new .so file with ln command.

This will help you to build the .so files.

Hope this helps.

JavaScript dictionary with names


var myMappings = {
    "Name":     "10%",
    "Phone":    "10%",
    "Address":  "50%",
    "Zip":      "10%",
    "Comments": "20%"

// Access is like this
myMappings["Name"] // Returns "10%"
myMappings.Name // The same thing as above

// To loop through...
for(var title in myMappings) {
    // Do whatever with myMappings[title]

How can I cast int to enum?

Just cast it:

MyEnum e = (MyEnum)3;

You can check if it's in range using Enum.IsDefined:

if (Enum.IsDefined(typeof(MyEnum), 3)) { ... }

Dynamically creating keys in a JavaScript associative array

Use the first example. If the key doesn't exist it will be added.

var a = new Array();
a['name'] = 'oscar';

Will pop up a message box containing 'oscar'.


var text = 'name = oscar'
var dict = new Array()
var keyValuePair = text.replace(/ /g,'').split('=');
dict[ keyValuePair[0] ] = keyValuePair[1];
alert( dict[keyValuePair[0]] );

Escape a string for a sed replace pattern

don't forget all the pleasure that occur with the shell limitation around " and '

so (in ksh)

Var=">New version of \"content' here <"
printf "%s" "${Var}" | sed "s/[&\/\\\\*\\"']/\\&/g' | read -r EscVar

echo "Here is your \"text\" to change" | sed "s/text/${EscVar}/g"

How to create a GUID/UUID using iOS

[[UIDevice currentDevice] uniqueIdentifier]

Returns the Unique ID of your iPhone.

EDIT: -[UIDevice uniqueIdentifier] is now deprecated and apps are being rejected from the App Store for using it. The method below is now the preferred approach.

If you need to create several UUID, just use this method (with ARC):

+ (NSString *)GetUUID
  CFStringRef string = CFUUIDCreateString(NULL, theUUID);
  return (__bridge NSString *)string;

EDIT: Jan, 29 2014: If you're targeting iOS 6 or later, you can now use the much simpler method:

NSString *UUID = [[NSUUID UUID] UUIDString];

What is "406-Not Acceptable Response" in HTTP?

"Sometimes" this can mean that the server had an internal error, and wanted to respond with an error message (ex: 500 with JSON payload) but since the request headers didn't say it accepted JSON, it returns a 406 instead. Go figure. (in this case: spring boot webapp).

In which case, your operation did fail. But the failure message was obscured by another.

Return multiple fields as a record in PostgreSQL with PL/pgSQL

you can do this using OUT parameter and CROSS JOIN

CREATE OR REPLACE FUNCTION get_object_fields(my_name text, OUT f1 text, OUT f2 text)
AS $$
FROM  table1 t1 
CROSS JOIN table2 t2 
WHERE = my_name AND = my_name;

then use it as a table:

select get_object_fields( 'Pending') ;
(1 row)


select * from get_object_fields( 'Pending');
f1    |   f
Pending | code
(1 row)


select (get_object_fields( 'Pending')).f1;
(1 row)

Difference between checkout and export in SVN

if you are using tortoise svn client - while exporting - it displays ..export / checkout , it is confusing , it is just export only. only view/read use export , to commit use - "checkout"

How can I convert a Timestamp into either Date or DateTime object?

java.sql.Timestamp is a subclass of java.util.Date. So, just upcast it.

Date dtStart = resultSet.getTimestamp("dtStart");
Date dtEnd = resultSet.getTimestamp("dtEnd");

Using SimpleDateFormat and creating Joda DateTime should be straightforward from this point on.

Get difference between two lists

Let's say we have two lists

list1 = [1, 3, 5, 7, 9]
list2 = [1, 2, 3, 4, 5]

we can see from the above two lists that items 1, 3, 5 exist in list2 and items 7, 9 do not. On the other hand, items 1, 3, 5 exist in list1 and items 2, 4 do not.

What is the best solution to return a new list containing items 7, 9 and 2, 4?

All answers above find the solution, now whats the most optimal?

def difference(list1, list2):
    new_list = []
    for i in list1:
        if i not in list2:

    for j in list2:
        if j not in list1:
    return new_list


def sym_diff(list1, list2):
    return list(set(list1).symmetric_difference(set(list2)))

Using timeit we can see the results

t1 = timeit.Timer("difference(list1, list2)", "from __main__ import difference, 
list1, list2")
t2 = timeit.Timer("sym_diff(list1, list2)", "from __main__ import sym_diff, 
list1, list2")

print('Using two for loops', t1.timeit(number=100000), 'Milliseconds')
print('Using two for loops', t2.timeit(number=100000), 'Milliseconds')


[7, 9, 2, 4]
Using two for loops 0.11572412995155901 Milliseconds
Using symmetric_difference 0.11285737506113946 Milliseconds

Process finished with exit code 0

Tools to generate database tables diagram with Postgresql?

Just found through the Postgres Community Guide mentioned by Frank Heikens. It can easily generate a diagram, and then lets you adjust the connectors!

Can Keras with Tensorflow backend be forced to use CPU or GPU at will?

This worked for me (win10), place before you import keras:

import os
os.environ['CUDA_VISIBLE_DEVICES'] = '-1'

Read specific columns from a csv file with csv module?

You can use numpy.loadtext(filename). For example if this is your database .csv:

ID | Name | Address | City | State | Zip | Phone | OPEID | IPEDS |
10 | Adam | 130 W.. | Mo.. | AL... | 3.. | 334.. | 01023 | 10063 |
10 | Carl | 130 W.. | Mo.. | AL... | 3.. | 334.. | 01023 | 10063 |
10 | Adolf | 130 W.. | Mo.. | AL... | 3.. | 334.. | 01023 | 10063 |
10 | Den | 130 W.. | Mo.. | AL... | 3.. | 334.. | 01023 | 10063 |

And you want the Name column:

import numpy as np 

>>> b
array([' Adam ', ' Carl ', ' Adolf ', ' Den '], 

More easily you can use genfromtext:

b = np.genfromtxt(r'filepath\name.csv', delimiter='|', names=True,dtype=None)
>>> b['Name']
array([' Adam ', ' Carl ', ' Adolf ', ' Den '], 

How do I delete files programmatically on Android?

Why don't you test this with this code:

File fdelete = new File(uri.getPath());
if (fdelete.exists()) {
    if (fdelete.delete()) {
        System.out.println("file Deleted :" + uri.getPath());
    } else {
        System.out.println("file not Deleted :" + uri.getPath());

I think part of the problem is you never try to delete the file, you just keep creating a variable that has a method call.

So in your case you could try:

File file = new File(uri.getPath());

However I think that's a little overkill.

You added a comment that you are using an external directory rather than a uri. So instead you should add something like:

String root = Environment.getExternalStorageDirectory().toString();
File file = new File(root + "/images/media/2918"); 

Then try to delete the file.

installing python packages without internet and using source code as .tar.gz and .whl

This isn't an answer. I was struggling but then realized that my install was trying to connect to internet to download dependencies.

So, I downloaded and installed dependencies first and then installed with below command. It worked

python -m pip install filename.tar.gz

Refused to load the script because it violates the following Content Security Policy directive

Adding the meta tag to ignore this policy was not helping us, because our webserver was injecting the Content-Security-Policy header in the response.

In our case we are using Ngnix as the web server for a Tomcat 9 Java-based application. From the web server, it is directing the browser not to allow inline scripts, so for a temporary testing we have turned off Content-Security-Policy by commenting.

How to turn it off in ngnix

  • By default, ngnix ssl.conf file will have this adding a header to the response:

    #> grep 'Content-Security' -ir /etc/nginx/global/ssl.conf add_header Content-Security-Policy "default-src 'none'; frame-ancestors 'none'; script-src 'self'; img-src 'self'; style-src 'self'; base-uri 'self'; form-action 'self';";

  • If you just comment this line and restart ngnix, it should not be adding the header to the response.

If you are concerned about security or in production please do not follow this, use these steps as only for testing purpose and moving on.

How to create a database from shell command?

mysqladmin -u$USER -p$PASSWORD create $DB_NAME

Replace above variables and you are good to go with this oneliner. $USER is the username, $PASSWORD is the password and $DB_NAME is the name of the database.

Using a remote repository with non-standard port

SSH based git access method can be specified in <repo_path>/.git/config using either a full URL or an SCP-like syntax, as specified in

URL style:

url = ssh://[user@]host.xz[:port]/path/to/repo.git/

SCP style:

url = [user@]host.xz:path/to/repo.git/

Notice that the SCP style does not allow a direct port change, relying instead on an ssh_config host definition in your ~/.ssh/config such as:

Host my_git_host
Port 24589
User not_a_root_user

Then you can test in a shell with:

ssh my_git_host

and alter your SCP-style URI in <repo_path>/.git/config as:

url = my_git_host:path/to/repo.git/

Configuring ObjectMapper in Spring

It may be because I'm using Spring 3.1 (instead of Spring 3.0.5 as your question specified), but Steve Eastwood's answer didn't work for me. This solution works for Spring 3.1:

In your spring xml context:

        <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
        <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>
        <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
            <property name="objectMapper" ref="jacksonObjectMapper" />

<bean id="jacksonObjectMapper" class="de.Company.backend.web.CompanyObjectMapper" />

How to initialize an array in Java?

Try data = new int[] {10,20,30,40,50,60,71,80,90,91 };

How do I change Bootstrap 3 column order on mobile layout?

In Bootstrap 4, if you want to do something like this:

    Mobile  |   Desktop
    A       |       A
    C       |   B       C
    B       |       D
    D       |

You need to reverse the order of B then C then apply order-{breakpoint}-first to B. And apply two different settings, one that will make them share the same cols and other that will make them take the full width of the 12 cols:

  • Smaller screens: 12 cols to B and 12 cols to C

  • Larger screens: 12 cols between the sum of them (B + C = 12)

Like this

<div class='row no-gutters'>
    <div class='col-12'>
    <div class='col-12'>
        <div class='row no-gutters'>
            <div class='col-12 col-md-6'>
            <div class='col-12 col-md-6 order-md-first'>
    <div class='col-12'>


Table columns, setting both min and max width with css

Tables work differently; sometimes counter-intuitively.

The solution is to use width on the table cells instead of max-width.

Although it may sound like in that case the cells won't shrink below the given width, they will actually.
with no restrictions on c, if you give the table a width of 70px, the widths of a, b and c will come out as 16, 42 and 12 pixels, respectively.
With a table width of 400 pixels, they behave like you say you expect in your grid above.
Only when you try to give the table too small a size (smaller than a.min+b.min+the content of C) will it fail: then the table itself will be wider than specified.

I made a snippet based on your fiddle, in which I removed all the borders and paddings and border-spacing, so you can measure the widths more accurately.

table {_x000D_
  width: 70px;_x000D_
table, tbody, tr, td {_x000D_
  margin: 0;_x000D_
  padding: 0;_x000D_
  border: 0;_x000D_
  border-spacing: 0;_x000D_
.a, .c {_x000D_
  background-color: red;_x000D_
.b {_x000D_
  background-color: #F77;_x000D_
.a {_x000D_
  min-width: 10px;_x000D_
  width: 20px;_x000D_
  max-width: 20px;_x000D_
.b {_x000D_
  min-width: 40px;_x000D_
  width: 45px;_x000D_
  max-width: 45px;_x000D_
.c {}
    <td class="a">A</td>_x000D_
    <td class="b">B</td>_x000D_
    <td class="c">C</td>_x000D_

How to add a new line in textarea element?

Break enter Keyword line in Textarea using CSS:

white-space: pre-wrap;

How to put the legend out of the plot

Short answer: you can use bbox_to_anchor + bbox_extra_artists + bbox_inches='tight'.

Longer answer: You can use bbox_to_anchor to manually specify the location of the legend box, as some other people have pointed out in the answers.

However, the usual issue is that the legend box is cropped, e.g.:

import matplotlib.pyplot as plt

# data 
all_x = [10,20,30]
all_y = [[1,3], [1.5,2.9],[3,2]]

# Plot
fig = plt.figure(1)
ax = fig.add_subplot(111)
ax.plot(all_x, all_y)

# Add legend, title and axis labels
lgd = ax.legend( [ 'Lag ' + str(lag) for lag in all_x], loc='center right', bbox_to_anchor=(1.3, 0.5))
ax.set_xlabel('x label')
ax.set_ylabel('y label')

fig.savefig('image_output.png', dpi=300, format='png')

enter image description here

In order to prevent the legend box from getting cropped, when you save the figure you can use the parameters bbox_extra_artists and bbox_inches to ask savefig to include cropped elements in the saved image:

fig.savefig('image_output.png', bbox_extra_artists=(lgd,), bbox_inches='tight')

Example (I only changed the last line to add 2 parameters to fig.savefig()):

import matplotlib.pyplot as plt

# data 
all_x = [10,20,30]
all_y = [[1,3], [1.5,2.9],[3,2]]

# Plot
fig = plt.figure(1)
ax = fig.add_subplot(111)
ax.plot(all_x, all_y)

# Add legend, title and axis labels
lgd = ax.legend( [ 'Lag ' + str(lag) for lag in all_x], loc='center right', bbox_to_anchor=(1.3, 0.5))
ax.set_xlabel('x label')
ax.set_ylabel('y label')    

fig.savefig('image_output.png', dpi=300, format='png', bbox_extra_artists=(lgd,), bbox_inches='tight')

enter image description here

I wish that matplotlib would natively allow outside location for the legend box as Matlab does:

x = 0:.2:12;
hleg = legend('First','Second','Third',...
% Make the text of the legend italic and color it brown

enter image description here

Return JsonResult from web api without its properties

As someone who has worked with ASP.NET API for about 3 years, I'd recommend returning an HttpResponseMessage instead. Don't use the ActionResult or IEnumerable!

ActionResult is bad because as you've discovered.

Return IEnumerable<> is bad because you may want to extend it later and add some headers, etc.

Using JsonResult is bad because you should allow your service to be extendable and support other response formats as well just in case in the future; if you seriously want to limit it you can do so using Action Attributes, not in the action body.

public HttpResponseMessage GetAllNotificationSettings()
    var result = new List<ListItems>();
    // Filling the list with data here...

    // Then I return the list
    return Request.CreateResponse(HttpStatusCode.OK, result);

In my tests, I usually use the below helper method to extract my objects from the HttpResponseMessage:

 public class ResponseResultExtractor
        public T Extract<T>(HttpResponseMessage response)
            return response.Content.ReadAsAsync<T>().Result;

var actual = ResponseResultExtractor.Extract<List<ListItems>>(response);

In this way, you've achieved the below:

  • Your Action can also return Error Messages and status codes like 404 not found so in the above way you can easily handle it.
  • Your Action isn't limited to JSON only but supports JSON depending on the client's request preference and the settings in the Formatter.

Look at this:

ASP.Net MVC: Calling a method from a view

Building on Amine's answer, create a helper like:

public static class HtmlHelperExtensions
    public static MvcHtmlString CurrencyFormat(this HtmlHelper helper, string value)
        var result = string.Format("{0:C2}", value);
        return new MvcHtmlString(result);

in your view: use @Html.CurrencyFormat(model.value)

If you are doing simple formating like Standard Numeric Formats, then simple use string.Format() in your view like in the helper example above:

@string.Format("{0:C2}", model.value)

How to send authorization header with axios

You are nearly correct, just adjust your code this way

const headers = { Authorization: `Bearer ${token}` };
return axios.get(URLConstants.USER_URL, { headers });

notice where I place the backticks, I added ' ' after Bearer, you can omit if you'll be sure to handle at the server-side

Search for "does-not-contain" on a DataFrame in pandas

Additional to nanselm2's answer, you can use 0 instead of False:


SQL Server: the maximum number of rows in table

Largest table I've encountered on SQL Server 8 on Windows2003 was 799 million with 5 columns. But whether or not it's good will is to be measured against the SLA and usage case - e.g. load 50-100,000,000 records and see if it still works.

Using arrays or std::vectors in C++, what's the performance gap?

Vectors are arrays under the hood. The performance is the same.

One place where you can run into a performance issue, is not sizing the vector correctly to begin with.

As a vector fills, it will resize itself, and that can imply, a new array allocation, followed by n copy constructors, followed by about n destructor calls, followed by an array delete.

If your construct/destruct is expensive, you are much better off making the vector the correct size to begin with.

There is a simple way to demonstrate this. Create a simple class that shows when it is constructed/destroyed/copied/assigned. Create a vector of these things, and start pushing them on the back end of the vector. When the vector fills, there will be a cascade of activity as the vector resizes. Then try it again with the vector sized to the expected number of elements. You will see the difference.

I want to execute shell commands from Maven's pom.xml

The problem here is that I don't know what is expected. With your current setup, invoking the plugin on the command line would just work:

$ mvn exec:exec
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building Q3491937
[INFO]    task-segment: [exec:exec]
[INFO] ------------------------------------------------------------------------
[INFO] [exec:exec {execution: default-cli}]
[INFO] laptop
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------

The global configuration is used, the hostname command is executed (laptop is my hostname). In other words, the plugin works as expected.

Now, if you want a plugin to get executed as part of the build, you have to bind a goal on a specific phase. For example, to bind it on compile:


And then:

$ mvn compile
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building Q3491937
[INFO]    task-segment: [compile]
[INFO] ------------------------------------------------------------------------
[INFO] [resources:resources {execution: default-resources}]
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /home/pascal/Projects/Q3491937/src/main/resources
[INFO] [compiler:compile {execution: default-compile}]
[INFO] Nothing to compile - all classes are up to date
[INFO] [exec:exec {execution: some-execution}]
[INFO] laptop
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------

Note that you can specify a configuration inside an execution.

How to convert Windows end of line in Unix end of line (CR/LF to LF)

The tr command can also do this:

tr -d '\15\32' < winfile.txt > unixfile.txt

and should be available to you.

You'll need to run tr from within a script, since it cannot work with file names. For example, create a file


for f in `find -iname \*.java`; do
    echo "$f"
    tr -d '\15\32' < "$f" > "$"
    mv "$" "$f"
    recode CP1252...UTF-8 "$f"

Running would process all the java files in the current directory and its subdirectories.

Spring get current ApplicationContext

There are many way to get application context in Spring application. Those are given bellow:

  1. Via ApplicationContextAware:

    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    public class AppContextProvider implements ApplicationContextAware {
    private ApplicationContext applicationContext;
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;

Here setApplicationContext(ApplicationContext applicationContext) method you will get the applicationContext

  1. Via Autowired:

    private ApplicationContext applicationContext;

Here @Autowired keyword will provide the applicationContext.

For more info visit this thread

Thanks :)

PHP Checking if the current date is before or after a set date

a MySQL-only solution would be something like this:

SELECT IF (UNIX_TIMESTAMP(`field`) > UNIX_TIMESTAMP(), `field`,'GO AHEAD') as `yourdate`
FROM `table`

Not an enclosing class error Android Studio

String user_email = email.getText().toString().trim();
    .addOnCompleteListener(new OnCompleteListener<AuthResult>() {
        public void onComplete(@NonNull Task<AuthResult> task) {
            if(task.isSuccessful()) {
                Toast.makeText(RegistraionActivity.this, "Registration sucessful", Toast.LENGTH_SHORT).show();
                startActivities(new Intent(RegistraionActivity.this,MainActivity.class));
                Toast.makeText(RegistraionActivity.this, "Registration failed", Toast.LENGTH_SHORT).show();

How can I loop through a List<T> and grab each item?

The low level iterator manipulate code:

List<Money> myMoney = new List<Money>
    new Money{amount = 10, type = "US"},
    new Money{amount = 20, type = "US"}
using (var enumerator = myMoney.GetEnumerator())
    while (enumerator.MoveNext())
        var element = enumerator.Current;

getElementsByClassName not working

There are several issues:

  1. Class names (and IDs) are not allowed to start with a digit.
  2. You have to pass a class to getElementsByClassName().
  3. You have to iterate of the result set.

Example (untested):

<script type="text/javascript">
function hideTd(className){
    var elements = document.getElementsByClassName(className);
    for(var i = 0, length = elements.length; i < length; i++) {
       if( elements[i].textContent == ''){
          elements[i].style.display = 'none';

<body onload="hideTd('td');">
<table border="1">
    <td class="td">not empty</td>
    <td class="td"></td>
    <td class="td"></td>

Note that getElementsByClassName() is not available up to and including IE8.


Alternatively you can give the table an ID and use:

var elements = document.getElementById('tableID').getElementsByTagName('td');

to get all td elements.

To hide the parent row, use the parentNode property of the element:

elements[i] = "none";

convert HTML ( having Javascript ) to PDF using JavaScript

Using the browser's Print... menu item, you can utilize a PDF Printer Driver, like PDFCreator. This way any JavaScript included in the page is processed by the browser when the page is rendered.

PDFCreator is a free tool to create PDF files from nearly any Windows application.

  • Create PDFs from any program that is able to print

git clone error: RPC failed; curl 56 OpenSSL SSL_read: SSL_ERROR_SYSCALL, errno 10054

Uninstalling(version: 2.19.2) and installing(version: 2.21.0) git client fixed the issue for me.

Sum one number to every element in a list (or array) in Python

using List Comprehension:

>>> L = [1]*5
>>> [x+1 for x in L]
[2, 2, 2, 2, 2]

which roughly translates to using a for loop:

>>> newL = []
>>> for x in L:
...     newL+=[x+1]
>>> newL
[2, 2, 2, 2, 2]

or using map:

>>> map(lambda x:x+1, L)
[2, 2, 2, 2, 2]

Ignore Typescript Errors "property does not exist on value of type"

There are several ways to handle this problem. If this object is related to some external library, the best solution would be to find the actual definitions file (great repository here) for that library and reference it, e.g.:

/// <reference path="/path/to/jquery.d.ts" >

Of course, this doesn't apply in many cases.

If you want to 'override' the type system, try the following:

declare var y;

This will let you make any calls you want on var y.

What is the difference between canonical name, simple name and class name in Java Class?

Adding local classes, lambdas and the toString() method to complete the previous two answers. Further, I add arrays of lambdas and arrays of anonymous classes (which do not make any sense in practice though):

package com.example;

public final class TestClassNames {
    private static void showClass(Class<?> c) {
        System.out.println("getName():          " + c.getName());
        System.out.println("getCanonicalName(): " + c.getCanonicalName());
        System.out.println("getSimpleName():    " + c.getSimpleName());
        System.out.println("toString():         " + c.toString());

    private static void x(Runnable r) {
        showClass(java.lang.reflect.Array.newInstance(r.getClass(), 1).getClass()); // Obtains an array class of a lambda base type.

    public static class NestedClass {}

    public class InnerClass {}

    public static void main(String[] args) {
        class LocalClass {}
        Object anonymous = new {};
        showClass(java.lang.reflect.Array.newInstance(anonymous.getClass(), 1).getClass()); // Obtains an array class of an anonymous base type.
        x(() -> {});

enum SomeEnum {

@interface SomeAnnotation {}

This is the full output:

getName():          void
getCanonicalName(): void
getSimpleName():    void
toString():         void

getName():          int
getCanonicalName(): int
getSimpleName():    int
toString():         int

getName():          java.lang.String
getCanonicalName(): java.lang.String
getSimpleName():    String
toString():         class java.lang.String

getName():          java.lang.Runnable
getCanonicalName(): java.lang.Runnable
getSimpleName():    Runnable
toString():         interface java.lang.Runnable

getName():          com.example.SomeEnum
getCanonicalName(): com.example.SomeEnum
getSimpleName():    SomeEnum
toString():         class com.example.SomeEnum

getName():          com.example.SomeAnnotation
getCanonicalName(): com.example.SomeAnnotation
getSimpleName():    SomeAnnotation
toString():         interface com.example.SomeAnnotation

getName():          [I
getCanonicalName(): int[]
getSimpleName():    int[]
toString():         class [I

getName():          [Ljava.lang.String;
getCanonicalName(): java.lang.String[]
getSimpleName():    String[]
toString():         class [Ljava.lang.String;

getName():          com.example.TestClassNames$NestedClass
getCanonicalName(): com.example.TestClassNames.NestedClass
getSimpleName():    NestedClass
toString():         class com.example.TestClassNames$NestedClass

getName():          com.example.TestClassNames$InnerClass
getCanonicalName(): com.example.TestClassNames.InnerClass
getSimpleName():    InnerClass
toString():         class com.example.TestClassNames$InnerClass

getName():          com.example.TestClassNames$1LocalClass
getCanonicalName(): null
getSimpleName():    LocalClass
toString():         class com.example.TestClassNames$1LocalClass

getName():          [Lcom.example.TestClassNames$1LocalClass;
getCanonicalName(): null
getSimpleName():    LocalClass[]
toString():         class [Lcom.example.TestClassNames$1LocalClass;

getName():          com.example.TestClassNames$1
getCanonicalName(): null
toString():         class com.example.TestClassNames$1

getName():          [Lcom.example.TestClassNames$1;
getCanonicalName(): null
getSimpleName():    []
toString():         class [Lcom.example.TestClassNames$1;

getName():          com.example.TestClassNames$$Lambda$1/1175962212
getCanonicalName(): com.example.TestClassNames$$Lambda$1/1175962212
getSimpleName():    TestClassNames$$Lambda$1/1175962212
toString():         class com.example.TestClassNames$$Lambda$1/1175962212

getName():          [Lcom.example.TestClassNames$$Lambda$1;
getCanonicalName(): com.example.TestClassNames$$Lambda$1/1175962212[]
getSimpleName():    TestClassNames$$Lambda$1/1175962212[]
toString():         class [Lcom.example.TestClassNames$$Lambda$1;

So, here are the rules. First, lets start with primitive types and void:

  1. If the class object represents a primitive type or void, all the four methods simply returns its name.

Now the rules for the getName() method:

  1. Every non-lambda and non-array class or interface (i.e, top-level, nested, inner, local and anonymous) has a name (which is returned by getName()) that is the package name followed by a dot (if there is a package), followed by the name of its class-file as generated by the compiler (whithout the suffix .class). If there is no package, it is simply the name of the class-file. If the class is an inner, nested, local or anonymous class, the compiler should generate at least one $ in its class-file name. Note that for anonymous classes, the class name would end with a dollar-sign followed by a number.
  2. Lambda class names are generally unpredictable, and you shouldn't care about they anyway. Exactly, their name is the name of the enclosing class, followed by $$Lambda$, followed by a number, followed by a slash, followed by another number.
  3. The class descriptor of the primitives are Z for boolean, B for byte, S for short, C for char, I for int, J for long, F for float and D for double. For non-array classes and interfaces the class descriptor is L followed by what is given by getName() followed by ;. For array classes, the class descriptor is [ followed by the class descriptor of the component type (which may be itself another array class).
  4. For array classes, the getName() method returns its class descriptor. This rule seems to fail only for array classes whose the component type is a lambda (which possibly is a bug), but hopefully this should not matter anyway because there is no point even on the existence of array classes whose component type is a lambda.

Now, the toString() method:

  1. If the class instance represents an interface (or an annotation, which is a special type of interface), the toString() returns "interface " + getName(). If it is a primitive, it returns simply getName(). If it is something else (a class type, even if it is a pretty weird one), it returns "class " + getName().

The getCanonicalName() method:

  1. For top-level classes and interfaces, the getCanonicalName() method returns just what the getName() method returns.
  2. The getCanonicalName() method returns null for anonymous or local classes and for array classes of those.
  3. For inner and nested classes and interfaces, the getCanonicalName() method returns what the getName() method would replacing the compiler-introduced dollar-signs by dots.
  4. For array classes, the getCanonicalName() method returns null if the canonical name of the component type is null. Otherwise, it returns the canonical name of the component type followed by [].

The getSimpleName() method:

  1. For top-level, nested, inner and local classes, the getSimpleName() returns the name of the class as written in the source file.
  2. For anonymous classes the getSimpleName() returns an empty String.
  3. For lambda classes the getSimpleName() just returns what the getName() would return without the package name. This do not makes much sense and looks like a bug for me, but there is no point in calling getSimpleName() on a lambda class to start with.
  4. For array classes the getSimpleName() method returns the simple name of the component class followed by []. This have the funny/weird side-effect that array classes whose component type is an anonymous class have just [] as their simple names.

How do I convert from a string to an integer in Visual Basic?

You can use the following to convert string to int:

  • CInt(String) for ints
  • CDec(String) for decimals

For details refer to Type Conversion Functions (Visual Basic).

What is the 'realtime' process priority setting for?

A realtime priority thread can never be pre-empted by timer interrupts and runs at a higher priority than any other thread in the system. As such a CPU bound realtime priority thread can totally ruin a machine.

Creating realtime priority threads requires a privilege (SeIncreaseBasePriorityPrivilege) so it can only be done by administrative users.

For Vista and beyond, one option for applications that do require that they run at realtime priorities is to use the Multimedia Class Scheduler Service (MMCSS) and let it manage your threads priority. The MMCSS will prevent your application from using too much CPU time so you don't have to worry about tanking the machine.

How can I get CMake to find my alternative Boost installation?

In CMake, you can add the following to your CMakelists:

# install boost by apt-get method
include_directories(BEFORE SYSTEM "/usr/include") 

#  or install by building from src
# include_directories(BEFORE SYSTEM "/usr/local/include") 

This method saved my serveral months. you can try it. By the way, as a temporary solution, you can rename directories you don't expect to find as below:

sudo mv /usr/local/include/boost /usr/local/include/boost_bak

Hopefully, it will help people who are in deep trouble like me.

Eclipse copy/paste entire line keyboard shortcut

Just another approach:

1) Alt+Up and Alt+Down (or Alt+Down and Alt+Up, order does not matter)
2) Ctrl+C

But of course vim's "yy" is the fastest :)

Reading a file character by character in C

I think the most significant problem is that you're incrementing code as you read stuff in, and then returning the final value of code, i.e. you'll be returning a pointer to the end of the string. You probably want to make a copy of code before the loop, and return that instead.

Also, C strings need to be null-terminated. You need to make sure that you place a '\0' directly after the final character that you read in.

Note: You could just use fgets() to get the entire line in one hit.

How to set bootstrap navbar active class with Angular JS?

This did the trick for me:

  var domain = '{{ DOMAIN }}'; // or
  var domain_index =  window.location.href.indexOf(domain);
  var long_app_name = window.location.href.slice(domain_index+domain.length+1); 
  // this turns to whatever/whatever
  app_name = long_app_name.slice(0, long_app_name.indexOf('/')); 
  //now you are left off with just the first whatever which is usually your app name

then you use jquery(works with angular too) to add class active

$('nav a[href*="' + app_name+'"]').closest('li').addClass('active');

and of course the css:


this works if you have your html like this:

<ul><li><a href="/ee">ee</a></li><li><a href="/dd">dd</a></li></ul>

this will atumatically add class active using the page url and color your background to red if your in thaen ee is the 'app' and it will be active

Java Read Large Text File With 70million line of text

enter image description hereI actually did a research in this topic for months in my free time and came up with a benchmark and here is a code to benchmark all the different ways to read a File line by line.The individual performance may vary based on the underlying system. I ran on a windows 10 Java 8 Intel i5 HP laptop:Here is the code.

import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.regex.Pattern;

public class ReadComplexDelimitedFile {
    private static long total = 0;
    private static final Pattern FIELD_DELIMITER_PATTERN = Pattern.compile("\\^\\|\\^");

    private void readFileUsingScanner() {

        String s;
        try (Scanner stdin = new Scanner(new File(this.getClass().getResource("input.txt").getPath()))) {
            while (stdin.hasNextLine()) {
                s = stdin.nextLine();
                String[] fields = FIELD_DELIMITER_PATTERN.split(s, 0);
                total = total + fields.length;
        } catch (Exception e) {


    private void readFileUsingCustomBufferedReader() {

        try (CustomBufferedReader stdin = new CustomBufferedReader(new FileReader(new File(this.getClass().getResource("input.txt").getPath())))) {
            String s;
            while ((s = stdin.readLine()) != null) {
                String[] fields = FIELD_DELIMITER_PATTERN.split(s, 0);
                total += fields.length;
        } catch (Exception e) {


    private void readFileUsingBufferedReader() {

        try (BufferedReader stdin = new BufferedReader(new FileReader(new File(this.getClass().getResource("input.txt").getPath())))) {
            String s;
            while ((s = stdin.readLine()) != null) {
                String[] fields = FIELD_DELIMITER_PATTERN.split(s, 0);
                total += fields.length;
        } catch (Exception e) {

    private void readFileUsingLineReader() {

        try (LineNumberReader stdin = new LineNumberReader(new FileReader(new File(this.getClass().getResource("input.txt").getPath())))) {
            String s;
            while ((s = stdin.readLine()) != null) {
                String[] fields = FIELD_DELIMITER_PATTERN.split(s, 0);
                total += fields.length;
        } catch (Exception e) {

    private void readFileUsingStreams() {

        try (Stream<String> stream = Files.lines((new File(this.getClass().getResource("input.txt").getPath())).toPath())) {
            total += stream.mapToInt(s -> FIELD_DELIMITER_PATTERN.split(s, 0).length).sum();
        } catch (IOException e1) {

    private void readFileUsingBufferedReaderFileChannel() {
        try (FileInputStream fis = new FileInputStream(this.getClass().getResource("input.txt").getPath())) {
            try (FileChannel inputChannel = fis.getChannel()) {
                try (CustomBufferedReader stdin = new CustomBufferedReader(Channels.newReader(inputChannel, "UTF-8"))) {
                    String s;
                    while ((s = stdin.readLine()) != null) {
                        String[] fields = FIELD_DELIMITER_PATTERN.split(s, 0);
                        total = total + fields.length;
            } catch (Exception e) {
        } catch (Exception e) {


    public static void main(String args[]) {
        //JVM wamrup
        for (int i = 0; i < 100000; i++) {
            total += i;
        // We know scanner is slow-Still warming up
        ReadComplexDelimitedFile readComplexDelimitedFile = new ReadComplexDelimitedFile();
        List<Long> longList = new ArrayList<>(50);
        for (int i = 0; i < 50; i++) {
            total = 0;
            long startTime = System.nanoTime();
            long stopTime = System.nanoTime();
            long timeDifference = stopTime - startTime;

        System.out.println("Time taken for readFileUsingScanner");
        // Actual performance test starts here

        longList = new ArrayList<>(10);
        for (int i = 0; i < 10; i++) {
            total = 0;
            long startTime = System.nanoTime();
            long stopTime = System.nanoTime();
            long timeDifference = stopTime - startTime;

        System.out.println("Time taken for readFileUsingBufferedReaderFileChannel");
        for (int i = 0; i < 10; i++) {
            total = 0;
            long startTime = System.nanoTime();
            long stopTime = System.nanoTime();
            long timeDifference = stopTime - startTime;

        System.out.println("Time taken for readFileUsingBufferedReader");
        for (int i = 0; i < 10; i++) {
            total = 0;
            long startTime = System.nanoTime();
            long stopTime = System.nanoTime();
            long timeDifference = stopTime - startTime;

        System.out.println("Time taken for readFileUsingStreams");
        for (int i = 0; i < 10; i++) {
            total = 0;
            long startTime = System.nanoTime();
            long stopTime = System.nanoTime();
            long timeDifference = stopTime - startTime;

        System.out.println("Time taken for readFileUsingCustomBufferedReader");
        for (int i = 0; i < 10; i++) {
            total = 0;
            long startTime = System.nanoTime();
            long stopTime = System.nanoTime();
            long timeDifference = stopTime - startTime;

        System.out.println("Time taken for readFileUsingLineReader");


I had to rewrite BufferedReader to avoid synchronized and a couple of boundary conditions that is not needed.(Atleast that's what I felt.It is not unit tested so use it at your own risk.)

import com.sun.istack.internal.NotNull;

import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

 * Reads text from a character-input stream, buffering characters so as to
 * provide for the efficient reading of characters, arrays, and lines.
 * <p>
 * <p> The buffer size may be specified, or the default size may be used.  The
 * default is large enough for most purposes.
 * <p>
 * <p> In general, each read request made of a Reader causes a corresponding
 * read request to be made of the underlying character or byte stream.  It is
 * therefore advisable to wrap a CustomBufferedReader around any Reader whose read()
 * operations may be costly, such as FileReaders and InputStreamReaders.  For
 * example,
 * <p>
 * <pre>
 * CustomBufferedReader in
 *   = new CustomBufferedReader(new FileReader(""));
 * </pre>
 * <p>
 * will buffer the input from the specified file.  Without buffering, each
 * invocation of read() or readLine() could cause bytes to be read from the
 * file, converted into characters, and then returned, which can be very
 * inefficient.
 * <p>
 * <p> Programs that use DataInputStreams for textual input can be localized by
 * replacing each DataInputStream with an appropriate CustomBufferedReader.
 * @author Mark Reinhold
 * @see FileReader
 * @see InputStreamReader
 * @see java.nio.file.Files#newBufferedReader
 * @since JDK1.1

public class CustomBufferedReader extends Reader {

    private final Reader in;

    private char cb[];
    private int nChars, nextChar;

    private static final int INVALIDATED = -2;
    private static final int UNMARKED = -1;
    private int markedChar = UNMARKED;
    private int readAheadLimit = 0; /* Valid only when markedChar > 0 */

     * If the next character is a line feed, skip it
    private boolean skipLF = false;

     * The skipLF flag when the mark was set
    private boolean markedSkipLF = false;

    private static int defaultCharBufferSize = 8192;
    private static int defaultExpectedLineLength = 80;
    private ReadWriteLock rwlock;

     * Creates a buffering character-input stream that uses an input buffer of
     * the specified size.
     * @param in A Reader
     * @param sz Input-buffer size
     * @throws IllegalArgumentException If {@code sz <= 0}
    public CustomBufferedReader(@NotNull final Reader in, int sz) {
        if (sz <= 0)
            throw new IllegalArgumentException("Buffer size <= 0"); = in;
        cb = new char[sz];
        nextChar = nChars = 0;
        rwlock = new ReentrantReadWriteLock();

     * Creates a buffering character-input stream that uses a default-sized
     * input buffer.
     * @param in A Reader
    public CustomBufferedReader(@NotNull final Reader in) {
        this(in, defaultCharBufferSize);

     * Fills the input buffer, taking the mark into account if it is valid.
    private void fill() throws IOException {
        int dst;
        if (markedChar <= UNMARKED) {
            /* No mark */
            dst = 0;
        } else {
            /* Marked */
            int delta = nextChar - markedChar;
            if (delta >= readAheadLimit) {
                /* Gone past read-ahead limit: Invalidate mark */
                markedChar = INVALIDATED;
                readAheadLimit = 0;
                dst = 0;
            } else {
                if (readAheadLimit <= cb.length) {
                    /* Shuffle in the current buffer */
                    System.arraycopy(cb, markedChar, cb, 0, delta);
                    markedChar = 0;
                    dst = delta;
                } else {
                    /* Reallocate buffer to accommodate read-ahead limit */
                    char ncb[] = new char[readAheadLimit];
                    System.arraycopy(cb, markedChar, ncb, 0, delta);
                    cb = ncb;
                    markedChar = 0;
                    dst = delta;
                nextChar = nChars = delta;

        int n;
        do {
            n =, dst, cb.length - dst);
        } while (n == 0);
        if (n > 0) {
            nChars = dst + n;
            nextChar = dst;

     * Reads a single character.
     * @return The character read, as an integer in the range
     * 0 to 65535 (<tt>0x00-0xffff</tt>), or -1 if the
     * end of the stream has been reached
     * @throws IOException If an I/O error occurs
    public char readChar() throws IOException {
        for (; ; ) {
            if (nextChar >= nChars) {
                if (nextChar >= nChars)
                    return (char) -1;
            return cb[nextChar++];

     * Reads characters into a portion of an array, reading from the underlying
     * stream if necessary.
    private int read1(char[] cbuf, int off, int len) throws IOException {
        if (nextChar >= nChars) {
            /* If the requested length is at least as large as the buffer, and
               if there is no mark/reset activity, and if line feeds are not
               being skipped, do not bother to copy the characters into the
               local buffer.  In this way buffered streams will cascade
               harmlessly. */
            if (len >= cb.length && markedChar <= UNMARKED && !skipLF) {
                return, off, len);
        if (nextChar >= nChars) return -1;
        int n = Math.min(len, nChars - nextChar);
        System.arraycopy(cb, nextChar, cbuf, off, n);
        nextChar += n;
        return n;

     * Reads characters into a portion of an array.
     * <p>
     * <p> This method implements the general contract of the corresponding
     * <code>{@link Reader#read(char[], int, int) read}</code> method of the
     * <code>{@link Reader}</code> class.  As an additional convenience, it
     * attempts to read as many characters as possible by repeatedly invoking
     * the <code>read</code> method of the underlying stream.  This iterated
     * <code>read</code> continues until one of the following conditions becomes
     * true: <ul>
     * <p>
     * <li> The specified number of characters have been read,
     * <p>
     * <li> The <code>read</code> method of the underlying stream returns
     * <code>-1</code>, indicating end-of-file, or
     * <p>
     * <li> The <code>ready</code> method of the underlying stream
     * returns <code>false</code>, indicating that further input requests
     * would block.
     * <p>
     * </ul> If the first <code>read</code> on the underlying stream returns
     * <code>-1</code> to indicate end-of-file then this method returns
     * <code>-1</code>.  Otherwise this method returns the number of characters
     * actually read.
     * <p>
     * <p> Subclasses of this class are encouraged, but not required, to
     * attempt to read as many characters as possible in the same fashion.
     * <p>
     * <p> Ordinarily this method takes characters from this stream's character
     * buffer, filling it from the underlying stream as necessary.  If,
     * however, the buffer is empty, the mark is not valid, and the requested
     * length is at least as large as the buffer, then this method will read
     * characters directly from the underlying stream into the given array.
     * Thus redundant <code>CustomBufferedReader</code>s will not copy data
     * unnecessarily.
     * @param cbuf Destination buffer
     * @param off  Offset at which to start storing characters
     * @param len  Maximum number of characters to read
     * @return The number of characters read, or -1 if the end of the
     * stream has been reached
     * @throws IOException If an I/O error occurs
    public int read(char cbuf[], int off, int len) throws IOException {
        int n = read1(cbuf, off, len);
        if (n <= 0) return n;
        while ((n < len) && in.ready()) {
            int n1 = read1(cbuf, off + n, len - n);
            if (n1 <= 0) break;
            n += n1;
        return n;

     * Reads a line of text.  A line is considered to be terminated by any one
     * of a line feed ('\n'), a carriage return ('\r'), or a carriage return
     * followed immediately by a linefeed.
     * @param ignoreLF If true, the next '\n' will be skipped
     * @return A String containing the contents of the line, not including
     * any line-termination characters, or null if the end of the
     * stream has been reached
     * @throws IOException If an I/O error occurs
     * @see
    String readLine(boolean ignoreLF) throws IOException {
        StringBuilder s = null;
        int startChar;

        for (; ; ) {

            if (nextChar >= nChars)
            if (nextChar >= nChars) { /* EOF */
                if (s != null && s.length() > 0)
                    return s.toString();
                    return null;
            boolean eol = false;
            char c = 0;
            int i;

            /* Skip a leftover '\n', if necessary */

            for (i = nextChar; i < nChars; i++) {
                c = cb[i];
                if ((c == '\n')) {
                    eol = true;
                    break charLoop;

            startChar = nextChar;
            nextChar = i;

            if (eol) {
                String str;
                if (s == null) {
                    str = new String(cb, startChar, i - startChar);
                } else {
                    s.append(cb, startChar, i - startChar);
                    str = s.toString();
                return str;

            if (s == null)
                s = new StringBuilder(defaultExpectedLineLength);
            s.append(cb, startChar, i - startChar);

     * Reads a line of text.  A line is considered to be terminated by any one
     * of a line feed ('\n'), a carriage return ('\r'), or a carriage return
     * followed immediately by a linefeed.
     * @return A String containing the contents of the line, not including
     * any line-termination characters, or null if the end of the
     * stream has been reached
     * @throws IOException If an I/O error occurs
     * @see java.nio.file.Files#readAllLines
    public String readLine() throws IOException {
        return readLine(false);

     * Skips characters.
     * @param n The number of characters to skip
     * @return The number of characters actually skipped
     * @throws IllegalArgumentException If <code>n</code> is negative.
     * @throws IOException              If an I/O error occurs
    public long skip(long n) throws IOException {
        if (n < 0L) {
            throw new IllegalArgumentException("skip value is negative");
            long r = n;
            while (r > 0) {
                if (nextChar >= nChars)
                if (nextChar >= nChars) /* EOF */
                if (skipLF) {
                    skipLF = false;
                    if (cb[nextChar] == '\n') {
                long d = nChars - nextChar;
                if (r <= d) {
                    nextChar += r;
                    r = 0;
                } else {
                    r -= d;
                    nextChar = nChars;
        } finally {
        return n - r;

     * Tells whether this stream is ready to be read.  A buffered character
     * stream is ready if the buffer is not empty, or if the underlying
     * character stream is ready.
     * @throws IOException If an I/O error occurs
    public boolean ready() throws IOException {
        try {
             * If newline needs to be skipped and the next char to be read
             * is a newline character, then just skip it right away.
            if (skipLF) {
                /* Note that in.ready() will return true if and only if the next
                 * read on the stream will not block.
                if (nextChar >= nChars && in.ready()) {
                if (nextChar < nChars) {
                    if (cb[nextChar] == '\n')
                    skipLF = false;
        } finally {
        return (nextChar < nChars) || in.ready();


     * Tells whether this stream supports the mark() operation, which it does.
    public boolean markSupported() {
        return true;

     * Marks the present position in the stream.  Subsequent calls to reset()
     * will attempt to reposition the stream to this point.
     * @param readAheadLimit Limit on the number of characters that may be
     *                       read while still preserving the mark. An attempt
     *                       to reset the stream after reading characters
     *                       up to this limit or beyond may fail.
     *                       A limit value larger than the size of the input
     *                       buffer will cause a new buffer to be allocated
     *                       whose size is no smaller than limit.
     *                       Therefore large values should be used with care.
     * @throws IllegalArgumentException If {@code readAheadLimit < 0}
     * @throws IOException              If an I/O error occurs
    public void mark(int readAheadLimit) throws IOException {
        if (readAheadLimit < 0) {
            throw new IllegalArgumentException("Read-ahead limit < 0");
        try {
            this.readAheadLimit = readAheadLimit;
            markedChar = nextChar;
            markedSkipLF = skipLF;
        } finally {

     * Resets the stream to the most recent mark.
     * @throws IOException If the stream has never been marked,
     *                     or if the mark has been invalidated
    public void reset() throws IOException {
        try {
            if (markedChar < 0)
                throw new IOException((markedChar == INVALIDATED)
                        ? "Mark invalid"
                        : "Stream not marked");
            nextChar = markedChar;
            skipLF = markedSkipLF;
        } finally {

    public void close() throws IOException {
        try {
        } finally {
            cb = null;


    public Stream<String> lines() {
        Iterator<String> iter = new Iterator<String>() {
            String nextLine = null;

            public boolean hasNext() {
                if (nextLine != null) {
                    return true;
                } else {
                    try {
                        nextLine = readLine();
                        return (nextLine != null);
                    } catch (IOException e) {
                        throw new UncheckedIOException(e);

            public String next() {
                if (nextLine != null || hasNext()) {
                    String line = nextLine;
                    nextLine = null;
                    return line;
                } else {
                    throw new NoSuchElementException();
                iter, Spliterator.ORDERED | Spliterator.NONNULL), false);

And now the results:

Time taken for readFileUsingBufferedReaderFileChannel 2902690903 1845190694 1894071377 1815161868 1861056735 1867693540 1857521371 1794176251 1768008762 1853089582

Time taken for readFileUsingBufferedReader 2022837353 1925901163 1802266711 1842689572 1899984555 1843101306 1998642345 1821242301 1820168806 1830375108

Time taken for readFileUsingStreams 1992855461 1930827034 1850876033 1843402533 1800378283 1863581324 1810857226 1798497108 1809531144 1796345853

Time taken for readFileUsingCustomBufferedReader 1759732702 1765987214 1776997357 1772999486 1768559162 1755248431 1744434555 1750349867 1740582606 1751390934

Time taken for readFileUsingLineReader 1845307174 1830950256 1829847321 1828125293 1827936280 1836947487 1832186310 1820276327 1830157935 1829171481

Process finished with exit code 0

Inference: The test was run on a 200 MB file. The test was repeated several times. The data looked like this

Start Date^|^Start Time^|^End Date^|^End Time^|^Event Title ^|^All Day Event^|^No End Time^|^Event Description^|^Contact ^|^Contact Email^|^Contact Phone^|^Location^|^Category^|^Mandatory^|^Registration^|^Maximum^|^Last Date To Register
9/5/2011^|^3:00:00 PM^|^9/5/2011^|^^|^Social Studies Dept. Meeting^|^N^|^Y^|^Department meeting^|^Chris Gallagher^|^[email protected]^|^814-555-5179^|^High School^|^2^|^N^|^N^|^25^|^9/2/2011

Bottomline not much difference between BufferedReader and my CustomReader and it is very miniscule and hence you can use this to read your file.

Trust me you don't have to break your head.use BufferedReader with readLine,it is properly tested.At worst if you feel you can improve it just override and change it to StringBuilder instead of StringBuffer just to shave off half a second

Difference between uint32 and uint32_t

uint32_t is defined in the standard, in

18.4.1 Header <cstdint> synopsis [cstdint.syn]

namespace std {
typedef unsigned integer type uint32_t; // optional

uint32 is not, it's a shortcut provided by some compilers (probably as typedef uint32_t uint32) for ease of use.

How is VIP swapping + CNAMEs better than IP swapping + A records?

A VIP swap is an internal change to Azure's routers/load balancers, not an external DNS change. They're just routing traffic to go from one internal [set of] server[s] to another instead. Therefore the DNS info for doesn't change at all. Therefore the change for people accessing via the IP bound to (and CNAME'd by you) will see the change as soon as the VIP swap is complete.

Using CMake to generate Visual Studio C++ project files

As Alex says, it works very well. The only tricky part is to remember to make any changes in the cmake files, rather than from within Visual Studio. So on all platforms, the workflow is similar to if you'd used plain old makefiles.

But it's fairly easy to work with, and I've had no issues with cmake generating invalid files or anything like that, so I wouldn't worry too much.

Echo tab characters in bash script

echo -e "[${res}]"

Looping through all rows in a table column, Excel-VBA

Assuming that your table is called 'Table1' and the column you need is 'Column' you can try this:

for i = 1 to Range("Table1").Rows.Count
next i

Number input type that takes only integers?

From the specs

step="any" or positive floating-point number
Specifies the value granularity of the element’s value.

So you could simply set it to 1:

Clicking a button within a form causes page refresh

I wonder why nobody proposed the possibly simplest solution:

don't use a <form>

A <whatever ng-form> does IMHO a better job and without an HTML form, there's nothing to be submitted by the browser itself. Which is exactly the right behavior when using angular.

How do I make entire div a link?

You need to assign display: block; property to the wrapping anchor. Otherwise it won't wrap correctly.

<a style="display:block" href="">
  <div class="xyz">My div contents</div>

Formatting NSDate into particular styles for both year, month, day, and hour, minute, seconds

this is what i used:

NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyy-MM-dd"];

NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
[timeFormat setDateFormat:@"HH:mm:ss"];

NSDate *now = [[NSDate alloc] init];

NSString *theDate = [dateFormat stringFromDate:now];
NSString *theTime = [timeFormat stringFromDate:now];

      "theDate: |%@| \n"
      "theTime: |%@| \n"
      , theDate, theTime);

[dateFormat release];
[timeFormat release];
[now release];

Using if elif fi in shell scripts

I have a sample from your code. Try this:

echo "*Select Option:*"
echo "1 - script1"
echo "2 - script2"
echo "3 - script3 "
read option
echo "You have selected" $option"."
if [ $option="1" ]
    echo "1"
elif [ $option="2" ]
    echo "2"
    exit 0
elif [ $option="3" ]
    echo "3"
    exit 0
    echo "Please try again from given options only."

This should work. :)

How can I save a base64-encoded image to disk?


I found this interesting link how to solve your problem in PHP. I think you forgot to replace space by +as shown in the link.

I took this circle from as sample which looks like:

Next I put it through which returned me:


saved this string to base64 which I read from in my code.

var fs      = require('fs'),
data        = fs.readFileSync('base64', 'utf8'),

base64Data  =   data.replace(/^data:image\/png;base64,/, "");
base64Data  +=  base64Data.replace('+', ' ');
binaryData  =   new Buffer(base64Data, 'base64').toString('binary');

fs.writeFile("out.png", binaryData, "binary", function (err) {
    console.log(err); // writes out file without error, but it's not a valid image

I get a circle back, but the funny thing is that the filesize has changed :)...


When you read back image I think you need to setup headers

Take for example imagepng from PHP page:

$im = imagecreatefrompng("test.png");

header('Content-Type: image/png');


I think the second line header('Content-Type: image/png');, is important else your image will not be displayed in browser, but just a bunch of binary data is shown to browser.

In Express you would simply just use something like below. I am going to display your gravatar which is located at and is a jpeg file when you curl --head I only request headers because else curl will display a bunch of binary stuff(Google Chrome immediately goes to download) to console:

curl --head ""
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 03 Aug 2011 12:11:25 GMT
Content-Type: image/jpeg
Connection: keep-alive
Last-Modified: Mon, 04 Oct 2010 11:54:22 GMT
Content-Disposition: inline; filename="cabf735ce7b8b4471ef46ea54f71832d.jpeg"
Access-Control-Allow-Origin: *
Content-Length: 1258
X-Varnish: 2356636561 2352219240
Via: 1.1 varnish
Expires: Wed, 03 Aug 2011 12:16:25 GMT
Cache-Control: max-age=300
Source-Age: 1482

$ mkdir -p ~/tmp/6922728
$ cd ~/tmp/6922728/
$ touch app.js


var app = require('express').createServer();

app.get('/', function (req, res) {

app.get('/binary', function (req, res) {


$ wget ""
$ node app.js

Best practice: PHP Magic Methods __set and __get

The best practice would be to use traditionnal getters and setters, because of introspection or reflection. There is a way in PHP (exactly like in Java) to obtain the name of a method or of all methods. Such a thing would return "__get" in the first case and "getFirstField", "getSecondField" in the second (plus setters).

More on that:

How do I check for a network connection?

You can check for a network connection in .NET 2.0 using GetIsNetworkAvailable():


To monitor changes in IP address or changes in network availability use the events from the NetworkChange class:


XML Error: There are multiple root elements

You need to enclose your <parent> elements in a surrounding element as XML Documents can have only one root node:

<parents> <!-- I've added this tag -->
</parents> <!-- I've added this tag -->

As you're receiving this markup from somewhere else, rather than generating it yourself, you may have to do this yourself by treating the response as a string and wrapping it with appropriate tags, prior to attempting to parse it as XML.

So, you've a couple of choices:

  1. Get the provider of the web service to return you actual XML that has one root node
  2. Pre-process the XML, as I've suggested above, to add a root node
  3. Pre-process the XML to split it into multiple chunks (i.e. one for each <parent> node) and process each as a distinct XML Document

Assign width to half available screen width declaratively

Using constraints layout

  1. Add a Guideline
  2. Set the percentage to 50%
  3. Constrain your view to the Guideline and the parent.

enter image description here

If you are having trouble changing it to a percentage, then see this answer.


<?xml version="1.0" encoding="utf-8"?>



Get Android Device Name

In order to get Android device name you have to add only a single line of code:


Found here: getting-android-device-name

PHP Error: Function name must be a string

It should be $_COOKIE['name'], not $_COOKIE('name')

$_COOKIE is an array, not a function.

How to execute an .SQL script file using c#

Put the command to execute the sql script into a batch file then run the below code

string batchFileName = @"c:\batosql.bat";
string sqlFileName = @"c:\MySqlScripts.sql";
Process proc = new Process();
proc.StartInfo.FileName = batchFileName;
proc.StartInfo.Arguments = sqlFileName;
proc.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
proc.StartInfo.ErrorDialog = false;
proc.StartInfo.WorkingDirectory = Path.GetDirectoryName(batchFileName);
if ( proc.ExitCode!= 0 )

in the batch file write something like this (sample for sql server)

osql -E -i %1

How to avoid warning when introducing NAs by coercion

suppressWarnings() has already been mentioned. An alternative is to manually convert the problematic characters to NA first. For your particular problem, taRifx::destring does just that. This way if you get some other, unexpected warning out of your function, it won't be suppressed.

> library(taRifx)
> x <- as.numeric(c("1", "2", "X"))
Warning message:
NAs introduced by coercion 
> y <- destring(c("1", "2", "X"))
> y
[1]  1  2 NA
> x
[1]  1  2 NA

How to execute a shell script from C in Linux?

I prefer fork + execlp for "more fine-grade" control as doron mentioned. Example code shown below.

Store you command in a char array parameters, and malloc space for the result.

int fd[2];
if ( (childpid = fork() ) == -1){
   fprintf(stderr, "FORK failed");
   return 1;
} else if( childpid == 0) {
   dup2(fd[1], 1);
read(fd[0], result, RESULT_SIZE);

How to make an HTTP get request with parameters

My preferred way is this. It handles the escaping and parsing for you.

WebClient webClient = new WebClient();
webClient.QueryString.Add("param1", "value1");
webClient.QueryString.Add("param2", "value2");
string result = webClient.DownloadString("");

Random number generator only generating one random number

I solved the problem by using the Rnd() function:

Function RollD6() As UInteger
        RollD6 = (Math.Floor(6 * Rnd())) + 1
        Return RollD6
End Function

When the form loads, I use the Randomize() method to make sure I don't always get the same sequence of random numbers from run to run.

belongs_to through associations

It sounds like what you want is a User who has many Questions.
The Question has many Answers, one of which is the User's Choice.

Is this what you are after?

I would model something like that along these lines:

class User
  has_many :questions

class Question
  belongs_to :user
  has_many   :answers
  has_one    :choice, :class_name => "Answer"

  validates_inclusion_of :choice, :in => lambda { answers }

class Answer
  belongs_to :question

How to copy marked text in notepad++

Try this instead:

First, fix the line ending problem: (Notepad++ doesn't allow multi-line regular expressions)

Search [Extended Mode]: \r\n> (Or your own system's line endings)

Replace: >


Search [Regex Mode]: <option[^>]+value="([^"]+)"[^>]*>.*

(if you want all occurences of value rather than just the options, simple remove the leading option)

Replace: \1

Explanation of the second regular expression:

<option[^>]+     Find a < followed by "option" followed by 
                 at least one character which is not a >

value="          Find the string value="

([^"]+)          Find one or more characters which are not a " and save them
                 to group \1

"[^>]*>.*        Find a " followed by zero or more non-'>' characters
                 followed by a > followed by zero or more characters.

Yes, it's parsing HTML with a regex -- these warnings apply -- check the output carefully.

Angular 5 ngHide ngShow [hidden] not working

2019 Update: I realize that this is somewhat bad advice. As the first comment states, this heavily depends on the situation, and it is not a bad practice to use the [hidden] attribute: see the comments for some of the cases where you need to use it and not *ngIf

Original answer:

You should always try to use *ngIf instead of [hidden].

 <input *ngIf="!isHidden" class="txt" type="password" [(ngModel)]="input_pw" >

There are several blog posts about that topics, but the bottom line is, that Hidden usually means you do not want the browser to render the object - using angular you still waste resource on rendering it, and it will end up in the DOM anyway (and tricky users can see it with basic browser manipulation).

Count unique values using pandas groupby

I think you can use SeriesGroupBy.nunique:

print (df.groupby('param')['group'].nunique())
a    2
b    1
Name: group, dtype: int64

Another solution with unique, then create new df by DataFrame.from_records, reshape to Series by stack and last value_counts:

a = df[df.param.notnull()].groupby('group')['param'].unique()
print (pd.DataFrame.from_records(a.values.tolist()).stack().value_counts())
a    2
b    1
dtype: int64

How to detect when an Android app goes to the background and come back to the foreground

The principal problem is that you have to get an specific behavior when you start an activity from background. If you override your onPause() and onResume() methods, you'll have a close answer, but not the solution. The problem is that onPause() and onResume() methods are called even if you don't minimize your application, they can be called when you start an activity and later you press the back button to return to your activity. To eliminate that problem and to know really when your application comes from background, you must to get the running process and compare with your process:

private boolean isApplicationBroughtToBackground() {
    ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
    List<RunningTaskInfo> tasks = am.getRunningTasks(1);
    if (!tasks.isEmpty()) {
        ComponentName topActivity = tasks.get(0).topActivity;
        if (!topActivity.getPackageName().equals(getPackageName())) {
            return true;
    return false;

Now you have to declare a boolean variable:

public boolean wasPaused = false;

And ask when your activity comes to background:

public void onPause(){
        wasPaused = true;

Now, when your activity comes to the screen again, ask in onResume() method:

public void onResume(){
    wasPaused = false;

And this is it. Now, when your activity comes to background, and later the user brings it to foreground, the lock screen will appear.

If you want to repeat this behavior for whatever activity of your app, you have to create an activity (could be BaseActivity), put this methods, and all your activities have to inherit from BaseActivity.

I hope that this help to you.


How do I debug a stand-alone VBScript script?

Export this folder to a backup file and try remove this folder and all the content.

HKEY_CURRENT_USER\Software\Microsoft\Script Debugger

WebService Client Generation Error with JDK8

Another alternative is to update shell script by adding the following:

The is located in this directory:


exec "$JAVA" $WSIMPORT_OPTS -Djavax.xml.accessExternalSchema=all -jar "$JAXWS_HOME/lib/jaxws-tools.jar" "$@"

How to reset a form using jQuery with .reset() method

This is one of those things that's actually easier done in vanilla Javascript than jQuery. jQuery doesn't have a reset method, but the HTML Form Element does, so you can reset all the fields in a form like this:


If you do this via jQuery (as seen in other answers here: $('#configform')[0].reset()), the [0] is fetching the same form DOM element that you would get directly via document.getElementById. The latter approach is both more efficient and simpler though (since with the jQuery approach you first get a collection and then have to fetch an element from it, whereas with the vanilla Javascript you just get the element directly).

What's the difference between including files with JSP include directive, JSP include action and using JSP Tag Files?

Main advantage of <jsp:include /> over <%@ include > is:

<jsp:include /> allows to pass parameters

<jsp:include page="inclusion.jsp">
    <jsp:param name="menu" value="objectValue"/>

which is not possible in <%@include file="somefile.jsp" %>

Getting the name of a variable as a string

This function will print variable name with its value:

import inspect

def print_this(var):
    callers_local_vars = inspect.currentframe().f_back.f_locals.items()
    print(str([k for k, v in callers_local_vars if v is var][0])+': '+str(var))
***Input & Function call:***
my_var = 10


my_var: 10

PHP-FPM and Nginx: 502 Bad Gateway

Try setting these values, it solves problem in fast-cgi

fastcgi_buffer_size 16k;
fastcgi_buffers 4 16k;

How to suppress binary file matching results in grep

This is an old question and its been answered but I thought I'd put the --binary-files=text option here for anyone who wants to use it. The -I option ignores the binary file but if you want the grep to treat the binary file as a text file use --binary-files=text like so:

bash$ grep -i reset mediaLog*
Binary file mediaLog_dc1.txt matches
bash$ grep --binary-files=text -i reset mediaLog*
mediaLog_dc1.txt:2016-06-29 15:46:02,470 - Media [uploadChunk  ,315] - ERROR - ('Connection aborted.', error(104, 'Connection reset by peer'))
mediaLog_dc1.txt:ConnectionError: ('Connection aborted.', error(104, 'Connection reset by peer'))

How to replace multiple strings in a file using PowerShell

One option is to chain the -replace operations together. The ` at the end of each line escapes the newline, causing PowerShell to continue parsing the expression on the next line:

$original_file = 'path\'
$destination_file =  'path\'
(Get-Content $original_file) | Foreach-Object {
    $_ -replace 'something1', 'something1aa' `
       -replace 'something2', 'something2bb' `
       -replace 'something3', 'something3cc' `
       -replace 'something4', 'something4dd' `
       -replace 'something5', 'something5dsf' `
       -replace 'something6', 'something6dfsfds'
    } | Set-Content $destination_file

Another option would be to assign an intermediate variable:

$x = $_ -replace 'something1', 'something1aa'
$x = $x -replace 'something2', 'something2bb'

Delete last char of string

strgroupids = strgroupids.Remove(strgroupids.Length - 1);



Deletes all the characters from this string beginning at a specified position and continuing through the last position

Time stamp in the C programming language

Standard C99:

#include <time.h>

time_t t0 = time(0);
// ...
time_t t1 = time(0);
double datetime_diff_ms = difftime(t1, t0) * 1000.;

clock_t c0 = clock();
// ...
clock_t c1 = clock();
double runtime_diff_ms = (c1 - c0) * 1000. / CLOCKS_PER_SEC;

The precision of the types is implementation-defined, ie the datetime difference might only return full seconds.

Frequency table for a single variable

You can use list comprehension on a dataframe to count frequencies of the columns as such

[my_series[c].value_counts() for c in list(my_series.select_dtypes(include=['O']).columns)]



Selects just the categorical data


Turns the columns from above into a list

[my_series[c].value_counts() for c in list(my_series.select_dtypes(include=['O']).columns)] 

Iterates through the list above and applies value_counts() to each of the columns

How to run Visual Studio post-build events for debug build only

Visual Studio 2015: The correct syntax is (keep it on one line):

if "$(ConfigurationName)"=="My Debug CFG" ( xcopy "$(TargetDir)test1.tmp" "$(TargetDir)test.xml" /y) else ( xcopy "$(TargetDir)test2.tmp" "$(TargetDir)test.xml" /y)

No error 255 here.

How to get today's Date?

Use this code to easy get Date & Time :

package date.time;

import java.text.SimpleDateFormat;    
import java.util.Date;

public class DateTime {

    public static void main(String[] args) {
        SimpleDateFormat dnt = new SimpleDateFormat("dd/MM/yy :: HH:mm:ss");
        Date date = new Date();
        System.out.println("Today Date & Time at Now :"+dnt.format(date));  

How to tell git to use the correct identity (name and email) for a given project?

You need to use the local set command below:

local set

git config [email protected]
git config 'Mahmoud Zalt'

local get

git config --get
git config --get

The local config file is in the project directory: .git/config.

global set

git config --global [email protected]
git config --global 'Mahmoud Zalt'

global get

git config --global --get
git config --global --get

The global config file in in your home directory: ~/.gitconfig.

Remember to quote blanks, etc, for example: 'FirstName LastName'

Remove DEFINER clause from MySQL Dumps

I don't think there is a way to ignore adding DEFINERs to the dump. But there are ways to remove them after the dump file is created.

  1. Open the dump file in a text editor and replace all occurrences of DEFINER=root@localhost with an empty string ""

  2. Edit the dump (or pipe the output) using perl:

    perl -p -i.bak -e "s/DEFINER=\`\w.*\`@\`\d[0-3].*[0-3]\`//g" mydatabase.sql
  3. Pipe the output through sed:

    mysqldump ... | sed -e 's/DEFINER[ ]*=[ ]*[^*]*\*/\*/' > triggers_backup.sql

How to fix warning from date() in PHP"

error_reporting(E_ALL ^ E_WARNING);


You should change subject to "How to fix warning from date() in PHP"...

JPA: How to get entity based on field value other than ID?

Edit: Just realized that @Chinmoy was getting at basically the same thing, but I think I may have done a better job ELI5 :)

If you're using a flavor of Spring Data to help persist / fetch things from whatever kind of Repository you've defined, you can probably have your JPA provider do this for you via some clever tricks with method names in your Repository interface class. Allow me to explain.

(As a disclaimer, I just a few moments ago did/still am figuring this out for myself.)

For example, if I am storing Tokens in my database, I might have an entity class that looks like this:

@Data // << Project Lombok convenience annotation
public class Token {
    @Column(name = "TOKEN_ID")
    private String tokenId;

    @Column(name = "TOKEN")
    private String token;

    @Column(name = "EXPIRATION")
    private String expiration;

    @Column(name = "SCOPE")
    private String scope;

And I probably have a CrudRepository<K,V> interface defined like this, to give me simple CRUD operations on that Repository for free.

// CrudRepository<{Entity Type}, {Entity Primary Key Type}>
public interface TokenRepository extends CrudRepository<Token, String> { }

And when I'm looking up one of these tokens, my purpose might be checking the expiration or scope, for example. In either of those cases, I probably don't have the tokenId handy, but rather just the value of a token field itself that I want to look up.

To do that, you can add an additional method to your TokenRepository interface in a clever way to tell your JPA provider that the value you're passing in to the method is not the tokenId, but the value of another field within the Entity class, and it should take that into account when it is generating the actual SQL that it will run against your database.

// CrudRepository<{Entity Type}, {Entity Primary Key Type}>
public interface TokenRepository extends CrudRepository<Token, String> { 
    List<Token> findByToken(String token);

I read about this on the Spring Data R2DBC docs page, and it seems to be working so far within a SpringBoot 2.x app storing in an embedded H2 database.

Multiple Forms or Multiple Submits in a Page?

Best practice: one form per product is definitely the way to go.


  • It will save you the hassle of having to parse the data to figure out which product was clicked
  • It will reduce the size of data being posted

In your specific situation

If you only ever intend to have one form element, in this case a submit button, one form for all should work just fine.

My recommendation Do one form per product, and change your markup to something like:

<form method="post" action="">
    <input type="hidden" name="product_id" value="123">
    <button type="submit" name="action" value="add_to_cart">Add to Cart</button>

This will give you a much cleaner and usable POST. No parsing. And it will allow you to add more parameters in the future (size, color, quantity, etc).

Note: There's no technical benefit to using <button> vs. <input>, but as a programmer I find it cooler to work with action=='add_to_cart' than action=='Add to Cart'. Besides, I hate mixing presentation with logic. If one day you decide that it makes more sense for the button to say "Add" or if you want to use different languages, you could do so freely without having to worry about your back-end code.

System.drawing namespace not found under console application

Add reference .dll file to project. Right, Click on Project reference folder --> click on Add Reference -->.Net tab you will find System.Drawing --> click on ok this will add a reference to System.Drawing

jQuery - select all text from a textarea

I ended up using this:

$('.selectAll').toggle(function() {
}, function() {

Could not find method android() for arguments

This error appear because the compiler could not found "my-upload-key.keystore" file in your project

After you have generated the file you need to paste it into project's andorid/app folder

this worked for me!

PHP Regex to check date is in YYYY-MM-DD format

You can make it this way:

if (preg_match("/\d{4}\-\d{2}-\d{2}/", $date)) {
    echo 'true';
} else {
    echo 'false';

but you'd better use this one:

$date = DateTime::createFromFormat('Y-m-d', $date);
if ($date) {
    echo $date -> format('Y-m-d');

in this case you'll get an object which is muck easier to use than just strings.

Java: Replace all ' in a string with \'

Let's take a tour of String#repalceAll(String regex, String replacement)

You will see that:

An invocation of this method of the form str.replaceAll(regex, repl) yields exactly the same result as the expression


So lets take a look at Matcher.html#replaceAll(java.lang.String) documentation

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string. Dollar signs may be treated as references to captured subsequences as described above, and backslashes are used to escape literal characters in the replacement string.

You can see that in replacement we have special character $ which can be used as reference to captured group like

System.out.println("aHellob,aWorldb".replaceAll("a(\\w+?)b", "$1"));
// result Hello,World

But sometimes we don't want $ to be such special because we want to use it as simple dollar character, so we need a way to escape it.
And here comes \, because since it is used to escape metacharacters in regex, Strings and probably in other places it is good convention to use it here to escape $.

So now \ is also metacharacter in replacing part, so if you want to make it simple \ literal in replacement you need to escape it somehow. And guess what? You escape it the same way as you escape it in regex or String. You just need to place another \ before one you escaping.

So if you want to create \ in replacement part you need to add another \ before it. But remember that to write \ literal in String you need to write it as "\\" so to create two \\ in replacement you need to write it as "\\\\".

So try

s = s.replaceAll("'", "\\\\'");

Or even better

to reduce explicit escaping in replacement part (and also in regex part - forgot to mentioned that earlier) just use replace instead replaceAll which adds regex escaping for us

s = s.replace("'", "\\'");

Creating a daemon in Linux

In Linux i want to add a daemon that cannot be stopped and which monitors filesystem changes. If any changes would be detected it should write the path to the console where it was started + a newline.

Daemons work in the background and (usually...) don't belong to a TTY that's why you can't use stdout/stderr in the way you probably want. Usually a syslog daemon (syslogd) is used for logging messages to files (debug, error,...).

Besides that, there are a few required steps to daemonize a process.

If I remember correctly these steps are:

  • fork off the parent process & let it terminate if forking was successful. -> Because the parent process has terminated, the child process now runs in the background.
  • setsid - Create a new session. The calling process becomes the leader of the new session and the process group leader of the new process group. The process is now detached from its controlling terminal (CTTY).
  • Catch signals - Ignore and/or handle signals.
  • fork again & let the parent process terminate to ensure that you get rid of the session leading process. (Only session leaders may get a TTY again.)
  • chdir - Change the working directory of the daemon.
  • umask - Change the file mode mask according to the needs of the daemon.
  • close - Close all open file descriptors that may be inherited from the parent process.

To give you a starting point: Look at this skeleton code that shows the basic steps. This code can now also be forked on GitHub: Basic skeleton of a linux daemon

 * daemonize.c
 * This example daemonizes a process, writes a few log messages,
 * sleeps 20 seconds and terminates afterwards.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <syslog.h>

static void skeleton_daemon()
    pid_t pid;

    /* Fork off the parent process */
    pid = fork();

    /* An error occurred */
    if (pid < 0)

    /* Success: Let the parent terminate */
    if (pid > 0)

    /* On success: The child process becomes session leader */
    if (setsid() < 0)

    /* Catch, ignore and handle signals */
    //TODO: Implement a working signal handler */
    signal(SIGCHLD, SIG_IGN);
    signal(SIGHUP, SIG_IGN);

    /* Fork off for the second time*/
    pid = fork();

    /* An error occurred */
    if (pid < 0)

    /* Success: Let the parent terminate */
    if (pid > 0)

    /* Set new file permissions */

    /* Change the working directory to the root directory */
    /* or another appropriated directory */

    /* Close all open file descriptors */
    int x;
    for (x = sysconf(_SC_OPEN_MAX); x>=0; x--)
        close (x);

    /* Open the log file */
    openlog ("firstdaemon", LOG_PID, LOG_DAEMON);
int main()

    while (1)
        //TODO: Insert daemon code here.
        syslog (LOG_NOTICE, "First daemon started.");
        sleep (20);

    syslog (LOG_NOTICE, "First daemon terminated.");

    return EXIT_SUCCESS;

  • Compile the code: gcc -o firstdaemon daemonize.c
  • Start the daemon: ./firstdaemon
  • Check if everything is working properly: ps -xj | grep firstdaemon

  • The output should be similar to this one:

|    1 | 3387 | 3386 | 3386 | ?   |    -1 | S    | 1000 | 0:00 | ./  |

What you should see here is:

  • The daemon has no controlling terminal (TTY = ?)
  • The parent process ID (PPID) is 1 (The init process)
  • The PID != SID which means that our process is NOT the session leader
    (because of the second fork())
  • Because PID != SID our process can't take control of a TTY again

Reading the syslog:

  • Locate your syslog file. Mine is here: /var/log/syslog
  • Do a: grep firstdaemon /var/log/syslog

  • The output should be similar to this one:

  firstdaemon[3387]: First daemon started.
  firstdaemon[3387]: First daemon terminated.

A note: In reality you would also want to implement a signal handler and set up the logging properly (Files, log levels...).

Further reading:

Html.HiddenFor value property not getting set

I believe there is a simpler solution. You must use Html.Hidden instead of Html.HiddenFor. Look:

@Html.Hidden("CRN", ViewData["crn"]);

This will create an INPUT tag of type="hidden", with id="CRN" and name="CRN", and the correct value inside the value attribute.

Hope it helps!

Android Animation Alpha

The "setStartOffset" should be smaller, else animation starts at view alpha 0.xf and waits for start offset before animating to 1f. Hope the following code helps.

AlphaAnimation animation1 = new AlphaAnimation(0.1f, 1f);





Format Float to n decimal places

Of note, use of DecimalFormat constructor is discouraged. The javadoc for this class states:

In general, do not call the DecimalFormat constructors directly, since the NumberFormat factory methods may return subclasses other than DecimalFormat.

So what you need to do is (for instance):

NumberFormat formatter = NumberFormat.getInstance(Locale.US);
Float formatedFloat = new Float(formatter.format(floatValue));

How to retrieve the last autoincremented ID from a SQLite table?

According to Android Sqlite get last insert row id there is another query:

SELECT rowid from your_table_name order by ROWID DESC limit 1

Chrome says my extension's manifest file is missing or unreadable

Something that commonly happens is that the manifest file isn't named properly. Double check the name (and extension) and be sure that it doesn't end with .txt (for example).

In order to determine this, make sure you aren't hiding file extensions:

  1. Open Windows Explorer
  2. Go to Folder and Search Options > View tab
  3. Uncheck Hide extensions for known file types

Also, note that the naming of the manifest file is, in fact, case sensitive, i.e. manifest.json != MANIFEST.JSON.

SQL-Server: Is there a SQL script that I can use to determine the progress of a SQL Server backup or restore process?

Yes. If you have installed sp_who2k5 into your master database, you can simply run:

sp_who2k5 1,1

The resultset will include all the active transactions. The currently running backup(s) will contain the string "BACKUP" in the requestCommand field. The aptly named percentComplete field will give you the progress of the backup.

Note: sp_who2k5 should be a part of everyone's toolkit, it does a lot more than just this.

java.text.ParseException: Unparseable date

Pattern is wrong

    String date="Sat Jun 01 12:53:10 IST 2013";
    SimpleDateFormat sdf=new SimpleDateFormat("E MMM dd hh:mm:ss Z yyyy");
    Date currentdate;

How to access route, post, get etc. parameters in Zend Framework 2

If You have no access to plugin for instance outside of controller You can get params from servicelocator like this

//from POST
$foo = $this->serviceLocator->get('request')->getPost('foo'); 
//from GET
$foo = $this->serviceLocator->get('request')->getQuery()->foo;
//from route
$foo = $this->serviceLocator->get('application')->getMvcEvent()->getRouteMatch()->getParam('foo');

What's the difference between all the Selection Segues?

Here is a quick summary of the segues and an example for each type.

Show - Pushes the destination view controller onto the navigation stack, sliding overtop from right to left, providing a back button to return to the source - or if not embedded in a navigation controller it will be presented modally
Example: Navigating inboxes/folders in Mail

Show Detail - For use in a split view controller, replaces the detail/secondary view controller when in an expanded 2 column interface, otherwise if collapsed to 1 column it will push in a navigation controller
Example: In Messages, tapping a conversation will show the conversation details - replacing the view controller on the right when in a two column layout, or push the conversation when in a single column layout

Present Modally - Presents a view controller in various animated fashions as defined by the Presentation option, covering the previous view controller - most commonly used to present a view controller that animates up from the bottom and covers the entire screen on iPhone, or on iPad it's common to present it as a centered box that darkens the presenting view controller
Example: Selecting Touch ID & Passcode in Settings

Popover Presentation - When run on iPad, the destination appears in a popover, and tapping anywhere outside of this popover will dismiss it, or on iPhone popovers are supported as well but by default it will present the destination modally over the full screen
Example: Tapping the + button in Calendar

Custom - You may implement your own custom segue and have control over its behavior

The deprecated segues are essentially the non-adaptive equivalents of those described above. These segue types were deprecated in iOS 8: Push, Modal, Popover, Replace.

For more info, you may read over the Using Segues documentation which also explains the types of segues and how to use them in a Storyboard. Also check out Session 216 Building Adaptive Apps with UIKit from WWDC 2014. They talked about how you can build adaptive apps using these new Adaptive Segues, and they built a demo project that utilizes these segues.

Retrieving Property name from lambda expression

This might be optimal

public static string GetPropertyName<TResult>(Expression<Func<TResult>> expr)
    var memberAccess = expr.Body as MemberExpression;
    var propertyInfo = memberAccess?.Member as PropertyInfo;
    var propertyName = propertyInfo?.Name;

    return propertyName;

Remove NA values from a vector

I ran a quick benchmark comparing the two base approaches and it turns out that x[!] is faster than na.omit. User qwr suggested I try purrr::dicard also - this turned out to be massively slower (though I'll happily take comments on my implementation & test!)

  purrr::map(airquality,function(x) {x[!]}), 
  purrr::map(airquality, ~purrr::discard(.x, .p =,
  times = 1e6)

Unit: microseconds
                                                     expr    min     lq      mean median      uq       max neval cld
 purrr::map(airquality, function(x) {     x[!] })   66.8   75.9  130.5643   86.2  131.80  541125.5 1e+06 a  
                          purrr::map(airquality, na.omit)   95.7  107.4  185.5108  129.3  190.50  534795.5 1e+06  b 
  purrr::map(airquality, ~purrr::discard(.x, .p = 3391.7 3648.6 5615.8965 4079.7 6486.45 1121975.4 1e+06   c

For reference, here's the original test of x[!] vs na.omit:

    purrr::map(airquality,function(x) {x[!]}), 
    times = 1000000)

Unit: microseconds
                                              expr  min   lq      mean median    uq      max neval cld
 map(airquality, function(x) {     x[!] }) 53.0 56.6  86.48231   58.1  64.8 414195.2 1e+06  a 
                          map(airquality, na.omit) 85.3 90.4 134.49964   92.5 104.9 348352.8 1e+06   b

Date in mmm yyyy format in postgresql


Breaking to a new line with inline-block?

Remove all br tags and use display: table.

.text span {
   background: rgba(165, 220, 79, 0.8);
   display: table;
   padding: 7px 10px;
   color: white;
.fullscreen .large { font-size: 80px }

Explanation: The table wraps the width of its content by default without setting a width, but is still a block level element. You can get the same behavior by setting a width to other block-level elements:

<span style="display:block;border:1px solid red;width:100px;">Like a default table.</span>

Notice the <code> element doesn't flow inline with the <span> like it would normally. Check it out with the computed styles in your dev tools. You'll see pseudo margin to the right of the <span>. Anyway, this is the same as the table, but the table has the added benefit of always forming to the width of its content.

How to make inline plots in Jupyter Notebook larger?

To adjust the size of one figure:

import matplotlib.pyplot as plt

fig=plt.figure(figsize=(15, 15))

To change the default settings, and therefore all your plots:

import matplotlib.pyplot as plt

plt.rcParams['figure.figsize'] = [15, 15]

Using number as "index" (JSON)

When a Javascript object property's name doesn't begin with either an underscore or a letter, you cant use the dot notation (like Game.status[0].0), and you must use the alternative notation, which is Game.status[0][0].

One different note, do you really need it to be an object inside the status array? If you're using the object like an array, why not use a real array instead?

$(document).on('click', '#id', function() {}) vs $('#id').on('click', function(){})

The first example demonstrates event delegation. The event handler is bound to an element higher up the DOM tree (in this case, the document) and will be executed when an event reaches that element having originated on an element matching the selector.

This is possible because most DOM events bubble up the tree from the point of origin. If you click on the #id element, a click event is generated that will bubble up through all of the ancestor elements (side note: there is actually a phase before this, called the 'capture phase', when the event comes down the tree to the target). You can capture the event on any of those ancestors.

The second example binds the event handler directly to the element. The event will still bubble (unless you prevent that in the handler) but since the handler is bound to the target, you won't see the effects of this process.

By delegating an event handler, you can ensure it is executed for elements that did not exist in the DOM at the time of binding. If your #id element was created after your second example, your handler would never execute. By binding to an element that you know is definitely in the DOM at the time of execution, you ensure that your handler will actually be attached to something and can be executed as appropriate later on.

Delete worksheet in Excel using VBA

Try this code:

For Each aSheet In Worksheets

    Select Case aSheet.Name

        Case "ID Sheet", "Summary"
            Application.DisplayAlerts = False
            Application.DisplayAlerts = True

    End Select

Next aSheet

How to initialize a list of strings (List<string>) with many string values

Your function is just fine but isn't working because you put the () after the last }. If you move the () to the top just next to new List<string>() the error stops.

Sample below:

List<string> optionList = new List<string>()

How do I detect what .NET Framework versions and service packs are installed?

The registry is the official way to detect if a specific version of the Framework is installed.

enter image description here

Which registry keys are needed change depending on the Framework version you are looking for:

Framework Version  Registry Key
1.0                HKLM\Software\Microsoft\.NETFramework\Policy\v1.0\3705 
1.1                HKLM\Software\Microsoft\NET Framework Setup\NDP\v1.1.4322\Install 
2.0                HKLM\Software\Microsoft\NET Framework Setup\NDP\v2.0.50727\Install 
3.0                HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.0\Setup\InstallSuccess 
3.5                HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.5\Install 
4.0 Client Profile HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Client\Install
4.0 Full Profile   HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Full\Install

Generally you are looking for:


except for .NET 1.0, where the value is a string (REG_SZ) rather than a number (REG_DWORD).

Determining the service pack level follows a similar pattern:

Framework Version  Registry Key
1.0                HKLM\Software\Microsoft\Active Setup\Installed Components\{78705f0d-e8db-4b2d-8193-982bdda15ecd}\Version 
1.0[1]             HKLM\Software\Microsoft\Active Setup\Installed Components\{FDC11A6F-17D1-48f9-9EA3-9051954BAA24}\Version 
1.1                HKLM\Software\Microsoft\NET Framework Setup\NDP\v1.1.4322\SP 
2.0                HKLM\Software\Microsoft\NET Framework Setup\NDP\v2.0.50727\SP 
3.0                HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.0\SP 
3.5                HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.5\SP 
4.0 Client Profile HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Client\Servicing
4.0 Full Profile   HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Full\Servicing

[1] Windows Media Center or Windows XP Tablet Edition

As you can see, determining the SP level for .NET 1.0 changes if you are running on Windows Media Center or Windows XP Tablet Edition. Again, .NET 1.0 uses a string value while all of the others use a DWORD.

For .NET 1.0 the string value at either of these keys has a format of #,#,####,#. The last # is the Service Pack level.

While I didn't explicitly ask for this, if you want to know the exact version number of the Framework you would use these registry keys:

Framework Version  Registry Key
1.0                HKLM\Software\Microsoft\Active Setup\Installed Components\{78705f0d-e8db-4b2d-8193-982bdda15ecd}\Version 
1.0[1]             HKLM\Software\Microsoft\Active Setup\Installed Components\{FDC11A6F-17D1-48f9-9EA3-9051954BAA24}\Version 
1.1                HKLM\Software\Microsoft\NET Framework Setup\NDP\v1.1.4322 
2.0[2]             HKLM\Software\Microsoft\NET Framework Setup\NDP\v2.0.50727\Version 
2.0[3]             HKLM\Software\Microsoft\NET Framework Setup\NDP\v2.0.50727\Increment
3.0                HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.0\Version 
3.5                HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.5\Version 
4.0 Client Profile HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Version 
4.0 Full Profile   HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Version 

[1] Windows Media Center or Windows XP Tablet Edition
[2] .NET 2.0 SP1
[3] .NET 2.0 Original Release (RTM)

Again, .NET 1.0 uses a string value while all of the others use a DWORD.

Additional Notes

  • for .NET 1.0 the string value at either of these keys has a format of #,#,####,#. The #,#,#### portion of the string is the Framework version.

  • for .NET 1.1, we use the name of the registry key itself, which represents the version number.

  • Finally, if you look at dependencies, .NET 3.0 adds additional functionality to .NET 2.0 so both .NET 2.0 and .NET 3.0 must both evaulate as being installed to correctly say that .NET 3.0 is installed. Likewise, .NET 3.5 adds additional functionality to .NET 2.0 and .NET 3.0, so .NET 2.0, .NET 3.0, and .NET 3. should all evaluate to being installed to correctly say that .NET 3.5 is installed.

  • .NET 4.0 installs a new version of the CLR (CLR version 4.0) which can run side-by-side with CLR 2.0.

Update for .NET 4.5

There won't be a v4.5 key in the registry if .NET 4.5 is installed. Instead you have to check if the HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Full key contains a value called Release. If this value is present, .NET 4.5 is installed, otherwise it is not. More details can be found here and here.

Press Enter to move to next control

This may help:

private void textBox1_KeyDown(object sender, KeyEventArgs e)
    // Detect the KeyEventArg's key enumerated constant.
    if (e.KeyCode == Keys.Enter)
        MessageBox.Show("You pressed enter! Good job!");

Ant is using wrong java version

You can use the target and source properties on the javac tag to set a target runtime. The example below will compile any source code to target version 1.4 on any compiler that supports version 1.4 or later.

<javac compiler="classic" taskname="javac" includeAntRuntime="no" fork=" deprecation="true" target="1.4" source="1.4" srcdir="${src}" destdir="${classes}">

Note: The 'srcdir' and 'destdir' are property values set else where in the build script, e.g. <property name="classes" value="c:/classes" />

Finishing current activity from a fragment

In Fragment use getActivity.finishAffinity()


It will remove all the fragment which pushed by the current activity from the Stack with the Activity too...

Refer to a cell in another worksheet by referencing the current worksheet's name?

Unless you want to go the VBA route to work out the Tab name, the Excel formula is fairly ugly based upon Mid functions, etc. But both these methods can be found here if you want to go that way.

Rather, the way I would do it is:

1) Make one cell on your sheet named, for example, Reference_Sheet and put in that cell the value "Jan Item" for example.

2) Now, use the Indirect function like:


3) Now, for each month's sheet, you just have to change that one Reference_Sheet cell.

Hope this gives you what you're looking for!

How to declare strings in C

Strings in C are represented as arrays of characters.

char *p = "String";

You are declaring a pointer that points to a string stored some where in your program (modifying this string is undefined behavior) according to the C programming language 2 ed.

char p2[] = "String";

You are declaring an array of char initialized with the string "String" leaving to the compiler the job to count the size of the array.

char p3[5] = "String";

You are declaring an array of size 5 and initializing it with "String". This is an error be cause "String" don't fit in 5 elements.

char p3[7] = "String"; is the correct declaration ('\0' is the terminating character in c strings).

TypeError: Missing 1 required positional argument: 'self'

You can call the method like pump.getPumps(). By adding @classmethod decorator on the method. A class method receives the class as the implicit first argument, just like an instance method receives the instance.

class Pump:

def __init__(self):
    print ("init") # never prints

def getPumps(cls):
            # Open database connection
            # some stuff here that never gets executed because of error

So, simply call Pump.getPumps() .

In java, it is termed as static method.

Accessing elements by type in javascript

var inputs = document.querySelectorAll("input[type=text]") ||
(function() {
    var ret=[], elems = document.getElementsByTagName('input'), i=0,l=elems.length;
    for (;i<l;i++) {
        if (elems[i].type.toLowerCase() === "text") {

    return ret;

Mapping list in Yaml to list of objects in Spring Boot

for me the fix was to add the injected class as inner class in the one annotated with @ConfigurationProperites, because I think you need @Component to inject properties.

How do you echo a 4-digit Unicode character in Bash?

So long as your text-editors can cope with Unicode (presumably encoded in UTF-8) you can enter the Unicode code-point directly.

For instance, in the Vim text-editor you would enter insert mode and press Ctrl + V + U and then the code-point number as a 4-digit hexadecimal number (pad with zeros if necessary). So you would type Ctrl + V + U 2 6 2 0. See: What is the easiest way to insert Unicode characters into a document?

At a terminal running Bash you would type CTRL+SHIFT+U and type in the hexadecimal code-point of the character you want. During input your cursor should show an underlined u. The first non-digit you type ends input, and renders the character. So you could be able to print U+2620 in Bash using the following:


(The first enter ends Unicode input, and the second runs the echo command.)

Credit: Ask Ubuntu SE

Make a table fill the entire window

That is because, of course, there is no ACTUAL page height. Keep in mind that you scroll throughout the contents of a page vertically not horizontally, creating a limited width but unlimited height. What the selected answer did was to make the table take up the visible area and stay there no matter what(absolute positioning).So theoretically what you were trying to do was impossible

How to print an exception in Python?

One liner error raising can be done with assert statements if that's what you want to do. This will help you write statically fixable code and check errors early.

assert type(A) is type(""), "requires a string"

How can I count the number of matches for a regex?

If you want to use Java 8 streams and are allergic to while loops, you could try this:

public static int countPattern(String references, Pattern referencePattern) {
    Matcher matcher = referencePattern.matcher(references);
    return Stream.iterate(0, i -> i + 1)
            .filter(i -> !matcher.find())

Disclaimer: this only works for disjoint matches.


public static void main(String[] args) throws ParseException {
    Pattern referencePattern = Pattern.compile("PASSENGER:\\d+");
    System.out.println(countPattern("[ \"PASSENGER:1\", \"PASSENGER:2\", \"AIR:1\", \"AIR:2\", \"FOP:2\" ]", referencePattern));
    System.out.println(countPattern("[ \"AIR:1\", \"AIR:2\", \"FOP:2\" ]", referencePattern));
    System.out.println(countPattern("[ \"AIR:1\", \"AIR:2\", \"FOP:2\", \"PASSENGER:1\" ]", referencePattern));
    System.out.println(countPattern("[  ]", referencePattern));

This prints out:


This is a solution for disjoint matches with streams:

public static int countPattern(String references, Pattern referencePattern) {
            new Iterator<Integer>() {
                Matcher matcher = referencePattern.matcher(references);
                int from = 0;

                public boolean hasNext() {
                    return matcher.find(from);

                public Integer next() {
                    from = matcher.start() + 1;
                    return 1;
            Spliterator.IMMUTABLE), false).reduce(0, (a, c) -> a + c);

How to pass variable as a parameter in Execute SQL Task SSIS?

The EXCEL and OLED DB connection managers use the parameter names 0 and 1.

I was using a oledb connection and wasted couple of hours trying to figure out the reason why the query was not working or taking the parameters. the above explanation helped a lot Thanks a lot.

C# if/then directives for debug vs release


using System.Resources;
using System.Diagnostics;


   private static bool IsDebug()
        object[] customAttributes = Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(DebuggableAttribute), false);
        if ((customAttributes != null) && (customAttributes.Length == 1))
            DebuggableAttribute attribute = customAttributes[0] as DebuggableAttribute;
            return (attribute.IsJITOptimizerDisabled && attribute.IsJITTrackingEnabled);
        return false;

Android, Java: HTTP POST Request

Please consider using HttpPost. Adopt from this:

URLConnection connection = new URL("").openConnection();
// Http Method becomes POST

// Encode according to application/x-www-form-urlencoded specification
String content =
    "id=" + URLEncoder.encode ("username") +
    "&num=" + URLEncoder.encode ("password") +
    "&remember=" + URLEncoder.encode ("on") +
    "&output=" + URLEncoder.encode ("xml");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); 

// Try this should be the length of you content.
// it is not neccessary equal to 48. 
// content.getBytes().length is not neccessarily equal to content.length() if the String contains non ASCII characters.
connection.setRequestProperty("Content-Length", content.getBytes().length); 

// Write body
OutputStream output = connection.getOutputStream(); 

You will need to catch the exception yourself.

Delete a closed pull request from GitHub

There is no way you can delete a pull request yourself -- you and the repo owner (and all users with push access to it) can close it, but it will remain in the log. This is part of the philosophy of not denying/hiding what happened during development.

However, if there are critical reasons for deleting it (this is mainly violation of Github Terms of Service), Github support staff will delete it for you.

Whether or not they are willing to delete your PR for you is something you can easily ask them, just drop them an email at [email protected]

UPDATE: Currently Github requires support requests to be created here:

How to export data from Excel spreadsheet to Sql Server 2008 table

There are several tools which can import Excel to SQL Server.

I am using DbTransfer ( to do the job. It's primarily focused on transfering data between databases and excel, xml, etc...

I have tried the openrowset method and the SQL Server Import / Export Assitant before. But I found these methods to be unnecessary complicated and error prone in constrast to doing it with one of the available dedicated tools.

Text File Parsing with Python

There are a few ways to go about this. One option would be to use instead of inputfile.readlines() - you'd need to write separate code to strip the first four lines, but if you want the final output as a single string anyway, this might make the most sense.

A second, simpler option would be to rejoin the strings after striping the first four lines with my_text = ''.join(my_text). This is a little inefficient, but if speed isn't a major concern, the code will be simplest.

Finally, if you actually want the output as a list of strings instead of a single string, you can just modify your data parser to iterate over the list. That might looks something like this:

def data_parser(lines, dic):
    for i, j in dic.iteritems():
        for (k, line) in enumerate(lines):
            lines[k] = line.replace(i, j)
    return lines

Maven build Compilation error : Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project Maven

for it was comming because of java version mismatch ,so I have corrected it and i am able to build the war file.hope it will help someone



categories_posts and categories_news start with substring 'categories_' then it is enough to check that developer_configurations_cms.cfg_name_unique starts with 'categories' instead of check if it contains the given substring. Translating all that into a query:

    FROM developer_configurations_cms

    WHERE developer_configurations_cms.cat_id = '1'
    AND developer_configurations_cms.cfg_variables LIKE '%parent_id=2%'
    AND developer_configurations_cms.cfg_name_unique NOT LIKE 'categories%'

Mockito How to mock and assert a thrown exception?

Or if your exception is thrown from the constructor of a class:

public ExpectedException exception = ExpectedException.none();

public void myTest() {    

    CustomClass myClass= mock(CustomClass.class);
    doThrow(new MyException("constructor failed")).when(myClass);  


What’s the best way to check if a file exists in C++? (cross platform)

How about access?

#include <io.h>

if (_access(filename, 0) == -1)
    // File does not exist

How to prevent a file from direct URL Access?

Try the following:

RewriteEngine on 
RewriteCond %{HTTP_REFERER} !^http://(www\.)?localhost [NC] 
RewriteCond %{HTTP_REFERER} !^http://(www\.)?localhost.*$ [NC] 
RewriteRule \.(gif|jpg)$ - [F]

Returns 403, if you access images directly, but allows them to be displayed on site.

Note: It is possible that when you open some page with image and then copy that image's path into the address bar you can see that image, it is only because of the browser's cache, in fact that image has not been loaded from the server (from Davo, full comment below).

Kill tomcat service running on any port, Windows

1) Go to (Open) Command Prompt (Press Window + R then type cmd Run this).

2) Run following commands

For all listening ports

netstat -aon | find /i "listening"

Apply port filter

netstat -aon |find /i "listening" |find "8080"

Finally with the PID we can run the following command to kill the process

3) Copy PID from result set

taskkill /F /PID

Ex: taskkill /F /PID 189

Sometimes you need to run Command Prompt with Administrator privileges

Done !!! you can start your service now.

Converting Stream to String and back...what are we missing?

a UTF8 MemoryStream to String conversion:

var res = Encoding.UTF8.GetString(stream.GetBuffer(), 0 , (int)stream.Length)

Comparing two dictionaries and checking how many (key, value) pairs are equal

see dictionary view objects:

This way you can subtract dictView2 from dictView1 and it will return a set of key/value pairs that are different in dictView2:

original = {'one':1,'two':2,'ACTION':'ADD'}
updatedDict = {'one':1,'two':2,'ACTION':'REPLACE'}
delta=original | updatedDict
print delta
>>set([('ACTION', 'REPLACE')])

You can intersect, union, difference (shown above), symmetric difference these dictionary view objects.
Better? Faster? - not sure, but part of the standard library - which makes it a big plus for portability

How do I get the web page contents from a WebView?

Have you considered fetching the HTML separately, and then loading it into a webview?

String fetchContent(WebView view, String url) throws IOException {
    HttpClient httpClient = new DefaultHttpClient();
    HttpGet get = new HttpGet(url);
    HttpResponse response = httpClient.execute(get);
    StatusLine statusLine = response.getStatusLine();
    int statusCode = statusLine.getStatusCode();
    HttpEntity entity = response.getEntity();
    String html = EntityUtils.toString(entity); // assume html for simplicity
    view.loadDataWithBaseURL(url, html, "text/html", "utf-8", url); // todo: get mime, charset from entity
    if (statusCode != 200) {
        // handle fail
    return html;

Get Today's date in Java at midnight time

If you are able to add external libs to your project. I would recommend that you try out Joda-time. It has a very clever way of working with dates.

Integer expression expected error in shell script

You can use this syntax:


echo " Write in your age: "
read age

if [[ "$age" -le 7 || "$age" -ge 65 ]] ; then
    echo " You can walk in for free "
elif [[ "$age" -gt 7 && "$age" -lt 65 ]] ; then
    echo " You have to pay for ticket "

Access to the path 'c:\inetpub\wwwroot\myapp\App_Data' is denied

Are you sure you are adding the correct user? Have you checked to see which user is set for your applications app pool?

This error will also happen if it cannot read the file for some reason; such as the file is locked or used by another application. Since this is an ASP.NET web application you will want to make sure you are not performing any actions that would require the file to be locked; unless you can guarantee you will only have one user on your page at a time.

Can you post an example of how you access the file? What type of file is it? Code snippets will help you get a more exact answer.

What should I use to open a url instead of urlopen in urllib3

You should use urllib.reuqest, not urllib3.

import urllib.request   # not urllib - important!

OpenCV resize fails on large image with "error: (-215) ssize.area() > 0 in function cv::resize"

Turns out for me this error was actually telling the truth - I was trying to resize a Null image, which was usually the 'last' frame of a video file, so the assertion was valid.

Now I have an extra step before attempting the resize operation, which is to do the assertion myself:

def getSizedFrame(width, height):
"""Function to return an image with the size I want"""    
    s, img =

    # Only process valid image frames
    if s:
            img = cv2.resize(img, (width, height), interpolation = cv2.INTER_AREA)
    return s, img

Now I don't see the error.

Java associative-array

Java doesn't have associative arrays, the closest thing you can get is the Map interface

Here's a sample from that page.

import java.util.*;

public class Freq {
    public static void main(String[] args) {
        Map<String, Integer> m = new HashMap<String, Integer>();

        // Initialize frequency table from command line
        for (String a : args) {
            Integer freq = m.get(a);
            m.put(a, (freq == null) ? 1 : freq + 1);

        System.out.println(m.size() + " distinct words:");

If run with:

java Freq if it is to be it is up to me to delegate

You'll get:

8 distinct words:
{to=3, delegate=1, be=1, it=2, up=1, if=1, me=1, is=2}

How to check if datetime happens to be Saturday or Sunday in SQL Server 2008

ok i figure out :

DECLARE @dayName VARCHAR(9), @weekenda VARCHAR(9), @free INT
SET @weekenda =DATENAME(dw,GETDATE())

IF (@weekenda='Saturday' OR @weekenda='Sunday')
SET @free=1
SET @free=0

than i use : .......... OR free=1

How to install pip for Python 3 on Mac OS X?

  1. brew install python3
  2. create alias in your shell profile

    • eg. alias pip3="python3 -m pip" in my .zshrc

? ~ pip3 --version

pip 9.0.1 from /usr/local/lib/python3.6/site-packages (python 3.6)

onclick="location.href='link.html'" does not load page in Safari

You can try this:

 <a href="link.html">
       <input type="button" value="Visit Page" />

This will create button inside a link and it works on any browser

How to find out when a particular table was created in Oracle?

You copy and paste the following code. It will display all the tables with Name and Created Date

SELECT object_name,created FROM user_objects
WHERE object_name LIKE  '%table_name%'
AND object_type = 'TABLE'; 

Note: Replace '%table_name%' with the table name you are looking for.

How to change heatmap.2 color range in R?

I think you need to set symbreaks = FALSE That should allow for asymmetrical color scales.

ORA-01036: illegal variable name/number when running query through C#

I was having the same problem in an application that I was maintaining, among all the adjustments to prepare the environment, I also spent almost an hour banging my head with this error "ORA-01036: illegal variable name / number" until I found out that the application connection was pointed to an outdated database, so the application passed two more parameters to the outdated database procedure causing the error.

What exactly is \r in C language?

Once upon a time, people had terminals like typewriters (with only upper-case letters, but that's another story). Search for 'Teletype', and how do you think tty got used for 'terminal device'?

Those devices had two separate motions. The carriage return moved the print head back to the start of the line without scrolling the paper; the line feed character moved the paper up a line without moving the print head back to the beginning of the line. So, on those devices, you needed two control characters to get the print head back to the start of the next line: a carriage return and a line feed. Because this was mechanical, it took time, so you had to pause for long enough before sending more characters to the terminal after sending the CR and LF characters. One use for CR without LF was to do 'bold' by overstriking the characters on the line. You'd write the line out once, then use CR to start over and print twice over the characters that needed to be bold. You could also, of course, type X's over stuff that you wanted partially hidden, or create very dense ASCII art pictures with judicious overstriking.

On Unix, all the logic for this stuff was hidden in a terminal driver. You could use the stty command and the underlying functions (in those days, ioctl() calls; they were sanitized into the termios interface by POSIX.1 in 1988) to tweak all sorts of ways that the terminal behaved.

Eventually, you got 'glass terminals' where the speeds were greater and and there were new idiosyncrasies to deal with - Hazeltine glitches and so on and so forth. These got enshrined in the termcap and later terminfo libraries, and then further encapsulated behind the curses library.

However, some other (non-Unix) systems did not hide things as well, and you had to deal with CRLF in your text files - and no, this is not just Windows and DOS that were in the 'CRLF' camp.

Anyway, on some systems, the C library has to deal with text files that contain CRLF line endings and presents those to you as if there were only a newline at the end of the line. However, if you choose to treat the text file as a binary file, you will see the CR characters as well as the LF.

Systems like the old Mac OS (version 9 or earlier) used just CR (aka \r) for the line ending. Systems like DOS and Windows (and, I believe, many of the DEC systems such as VMS and RSTS) used CRLF for the line ending. Many of the Internet standards (such as mail) mandate CRLF line endings. And Unix has always used just LF (aka NL or newline, hence \n) for its line endings. And most people, most of the time, manage to ignore CR.

Your code is rather funky in looking for \r. On a system compliant with the C standard, you won't see the CR unless the file is opened in binary mode; the CRLF or CR will be mapped to NL by the C runtime library.

Pass C# ASP.NET array to Javascript array

Here is another alternative solution. You can use ClientScriptManager Page.ClientScript.RegisterArrayDeclaration. Here is an example for chart data.

var page = HttpContext.Current.CurrentHandler as Page;

_data = "[Date.UTC(2018, 9, 29, 0, 3), parseFloat(21.84)]
         ,[Date.UTC(2018, 9, 29, 0, 13), parseFloat(21.84)]
         ,[Date.UTC(2018, 9, 29, 0, 23), parseFloat(21.83)]
         ,[Date.UTC(2018, 9, 29, 0, 33), parseFloat(21.83)]";
page.ClientScript.RegisterArrayDeclaration("chartdata0", _data);

This code creates an array on the client side

var chartdata0 = new Array([Date.UTC(2018, 9, 29, 0, 3), parseFloat(21.84)]
             ,[Date.UTC(2018, 9, 29, 0, 13), parseFloat(21.84)]
             ,[Date.UTC(2018, 9, 29, 0, 23), parseFloat(21.83)]
             ,[Date.UTC(2018, 9, 29, 0, 33), parseFloat(21.83)]);

See the following article

This solution has an issue with bigger arrays on chrome 64 browser including "Version 78.0.3904.70 (Official Build) (64-bit)". You may get "Uncaught RangeError: Maximum call stack size exceeded". However it is working with IE11, Microsoft Edge, and FireFox.

How to go to a URL using jQuery?

//As an HTTP redirect (back button will not work )

//like if you click on a link (it will be saved in the session history, 
//so the back button will work as expected)
window.location.href = "";

Choose File Dialog

Was looking for a file/folder browser myself recently and decided to make a new explorer activity (Android library):

Matching Test application is a sample how to use.

Allows picking directories and files from phone file structure.

__FILE__ macro shows full path

GCC 8 now has the -fmacro-prefix-map and -ffile-prefix-map options:


When preprocessing files residing in directory old, expand the __FILE__ and __BASE_FILE__ macros as if the files resided in directory new instead. This can be used to change an absolute path to a relative path by using . for new which can result in more reproducible builds that are location independent. This option also affects __builtin_FILE() during compilation. See also -ffile-prefix-map.


When compiling files residing in directory old, record any references to them in the result of the compilation as if the files resided in directory new instead. Specifying this option is equivalent to specifying all the individual -f*-prefix-map options. This can be used to make reproducible builds that are location independent. See also -fmacro-prefix-map and -fdebug-prefix-map.

Setting an invalid path for -ffile-prefix-map (-fdebug-prefix-map) will break debugging unless you tell your debugger how to map back. (gdb: set substitue-path, vscode: "sourceFileMap").

If your intent is to only clean up __FILE__ just use -fmacro-prefix-map.

Example: So for my Jenkins builds I will add -ffile-prefix-map=${WORKSPACE}/=/, and another to remove the local dev package install prefix.

NOTE Unfortunately the -ffile-prefix-map and -fmacro-prefix-map options are only available in GCC 8 onwards. For, say, GCC 5, we only have -fdebug-prefix-map which does not affect __FILE__.

Ternary operator in AngularJS templates

While you can use the condition && if-true-part || if-false-part-syntax in older versions of angular, the usual ternary operator condition ? true-part : false-part is available in Angular 1.1.5 and later.

sklearn: Found arrays with inconsistent numbers of samples when calling

Looks like you are using pandas dataframe (from the name df2).

You could also do the following:

regr = LinearRegression()[1:1000, 5].to_frame(), df2.iloc[1:1000, 2].to_frame())

NOTE: I have removed "values" as that converts the pandas Series to numpy.ndarray and numpy.ndarray does not have attribute to_frame().

How do I select which GPU to run a job on?

Set the following two environment variables:


where gpu_id is the ID of your selected GPU, as seen in the host system's nvidia-smi (a 0-based integer) that will be made available to the guest system (e.g. to the Docker container environment).

You can verify that a different card is selected for each value of gpu_id by inspecting Bus-Id parameter in nvidia-smi run in a terminal in the guest system).

More info

This method based on NVIDIA_VISIBLE_DEVICES exposes only a single card to the system (with local ID zero), hence we also hard-code the other variable, CUDA_VISIBLE_DEVICES to 0 (mainly to prevent it from defaulting to an empty string that would indicate no GPU).

Note that the environmental variable should be set before the guest system is started (so no chances of doing it in your Jupyter Notebook's terminal), for instance using docker run -e NVIDIA_VISIBLE_DEVICES=0 or env in Kubernetes or Openshift.

If you want GPU load-balancing, make gpu_id random at each guest system start.

If setting this with python, make sure you are using strings for all environment variables, including numerical ones.

You can verify that a different card is selected for each value of gpu_id by inspecting nvidia-smi's Bus-Id parameter (in a terminal run in the guest system).

The accepted solution based on CUDA_VISIBLE_DEVICES alone does not hide other cards (different from the pinned one), and thus causes access errors if you try to use them in your GPU-enabled python packages. With this solution, other cards are not visible to the guest system, but other users still can access them and share their computing power on an equal basis, just like with CPU's (verified).

This is also preferable to solutions using Kubernetes / Openshift controlers (, that would impose a lock on the allocated card, removing it from the pool of available resources (so the number of containers with GPU access could not exceed the number of physical cards).

This has been tested under CUDA 8.0, 9.0 and 10.1 in docker containers running Ubuntu 18.04 orchestrated by Openshift 3.11.

How to use python numpy.savetxt to write strings and float number to an ASCII file?

The currently accepted answer does not actually address the question, which asks how to save lists that contain both strings and float numbers. For completeness I provide a fully working example, which is based, with some modifications, on the link given in @joris comment.

import numpy as np

names  = np.array(['NAME_1', 'NAME_2', 'NAME_3'])
floats = np.array([ 0.1234 ,  0.5678 ,  0.9123 ])

ab = np.zeros(names.size, dtype=[('var1', 'U6'), ('var2', float)])
ab['var1'] = names
ab['var2'] = floats

np.savetxt('test.txt', ab, fmt="%10s %10.3f")

Update: This example also works properly in Python 3 by using the 'U6' Unicode string dtype, when creating the ab structured array, instead of the 'S6' byte string. The latter dtype would work in Python 2.7, but would write strings like b'NAME_1' in Python 3.

good example of Javadoc

The page How to Write Doc Coments for the Javadoc Tool contains a good number of good examples. One section is called Examples of Doc Comments and contains quite a few usages.

Also, the Javadoc FAQ contains some more examples to illustrate the answers.

Automapper missing type map configuration or unsupported mapping - Error

In my case, I had created the map, but was missing the ReverseMap function. Adding it got rid of the error.

      private static void RegisterServices(ContainerBuilder bldr)
         var config = new MapperConfiguration(cfg =>
            cfg.AddProfile(new CampMappingProfile());

      public CampMappingProfile()
         CreateMap<Talk, TalkModel>().ReverseMap();

Writing to a TextBox from another thread?

You need to perform the action from the thread that owns the control.

That's how I'm doing that without adding too much code noise:

control.Invoke(() => textBox1.Text += "hi");

Where Invoke overload is a simple extension from Lokad Shared Libraries:

/// <summary>
/// Invokes the specified <paramref name="action"/> on the thread that owns     
/// the <paramref name="control"/>.</summary>
/// <typeparam name="TControl">type of the control to work with</typeparam>
/// <param name="control">The control to execute action against.</param>
/// <param name="action">The action to on the thread of the control.</param>
public static void Invoke<TControl>(this TControl control, Action action) 
  where TControl : Control
  if (!control.InvokeRequired)

How do I check that a Java String is not all whitespaces?

Slightly shorter than what was mentioned by Carl Smotricz:


How to resolve /var/www copy/write permission denied?

First off, this has nothing to do with php. This is a unix permission issue. You need to login as a superuser ( sudo/su ) and type your password, then try that command.

$ su
(type password )
\# your command

$ sudo command
$ (type password)

It might also help if you actually specified the operating system you use.

What does "publicPath" in Webpack do?

You can use publicPath to point to the location where you want webpack-dev-server to serve its "virtual" files. The publicPath option will be the same location of the content-build option for webpack-dev-server. webpack-dev-server creates virtual files that it will use when you start it. These virtual files resemble the actual bundled files webpack creates. Basically you will want the --content-base option to point to the directory your index.html is in. Here is an example setup:

//application directory structure

var path = require("path");
module.exports = {
  output: {
    path: path.resolve(__dirname, "build"),
    publicPath: "/assets/",
    filename: "bundle.js"

<script src="assets/bundle.js"></script>

//starting a webpack-dev-server from the command line
$ webpack-dev-server --content-base build 

webpack-dev-server has created a virtual assets folder along with a virtual bundle.js file that it refers to. You can test this by going to localhost:8080/assets/bundle.js then check in your application for these files. They are only generated when you run the webpack-dev-server.