Programs & Examples On #Prerequesthandler

Check if element exists in jQuery

Try to check the length of the selector, if it returns you something then the element must exists else not.

 if( $('#selector').length )         // use this if you are using id to check
{
     // it exists
}


 if( $('.selector').length )         // use this if you are using class to check
{
     // it exists
}

How to get the latest file in a folder?

Try to sort items by creation time. Example below sorts files in a folder and gets first element which is latest.

import glob
import os

files_path = os.path.join(folder, '*')
files = sorted(
    glob.iglob(files_path), key=os.path.getctime, reverse=True) 
print files[0]

How to generate a random number between 0 and 1?

Set the seed using srand(). Also, you're not specifying the max value in rand(), so it's using RAND_MAX. I'm not sure if it's actually 10000... why not just specify it. Although, we don't know what your "expected results" are. It's a random number generator. What are you expecting, and what are you seeing?

As noted in another comment, SA() isn't returning anything explicitly.

http://pubs.opengroup.org/onlinepubs/009695399/functions/rand.html http://www.thinkage.ca/english/gcos/expl/c/lib/rand.html

Edit: From Generating random number between [-1, 1] in C? ((float)rand())/RAND_MAX returns a floating-point number in [0,1]

How to bind to a PasswordBox in MVVM

you can do it with attached property, see it.. PasswordBox with MVVM

Width equal to content

Using display:inline-block; it will work only for a correct sentence with spaces like

_x000D_
_x000D_
#container {_x000D_
    width: 30%;_x000D_
    background-color: grey;_x000D_
    overflow:hidden;_x000D_
    margin:10px;_x000D_
}_x000D_
#container p{_x000D_
    display:inline-block;_x000D_
    background-color: green;_x000D_
}
_x000D_
<h5>Correct sentence with spaces </h5>_x000D_
<div id="container">_x000D_
    <p>Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1</p>_x000D_
</div>_x000D_
<h5>No specaes (not working )</h5>_x000D_
<div id="container">_x000D_
    <p>SampleSampleSampleSampleSampleSampleSampleSampleSampleSampleSamplesadasdsadasdasdsa</p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Why not using word-wrap: break-word;? it's made to allow long words to be able to break and wrap onto the next line.

_x000D_
_x000D_
#container {_x000D_
    width: 30%;_x000D_
    background-color: grey;_x000D_
    overflow:hidden;_x000D_
    margin:10px;_x000D_
}_x000D_
#container p{_x000D_
   word-wrap: break-word;_x000D_
    background-color: green;_x000D_
}
_x000D_
<h5> Correct sentence with spaces </h5>_x000D_
<div id="container">_x000D_
    <p>Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1</p>_x000D_
</div>_x000D_
<h5>No specaes</h5>_x000D_
<div id="container">_x000D_
    <p>SampleSampleSampleSampleSampleSampleSampleSampleSampleSampleSamplesadasdsadasdasdsa</p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

sklearn error ValueError: Input contains NaN, infinity or a value too large for dtype('float64')

In my case the problem was that many scikit functions return numpy arrays, which are devoid of pandas index. So there was an index mismatch when I used those numpy arrays to build new DataFrames and then I tried to mix them with the original data.

How to do a FULL OUTER JOIN in MySQL?

The answer that Pablo Santa Cruz gave is correct; however, in case anybody stumbled on this page and wants more clarification, here is a detailed breakdown.

Example Tables

Suppose we have the following tables:

-- t1
id  name
1   Tim
2   Marta

-- t2
id  name
1   Tim
3   Katarina

Inner Joins

An inner join, like this:

SELECT *
FROM `t1`
INNER JOIN `t2` ON `t1`.`id` = `t2`.`id`;

Would get us only records that appear in both tables, like this:

1 Tim  1 Tim

Inner joins don't have a direction (like left or right) because they are explicitly bidirectional - we require a match on both sides.

Outer Joins

Outer joins, on the other hand, are for finding records that may not have a match in the other table. As such, you have to specify which side of the join is allowed to have a missing record.

LEFT JOIN and RIGHT JOIN are shorthand for LEFT OUTER JOIN and RIGHT OUTER JOIN; I will use their full names below to reinforce the concept of outer joins vs inner joins.

Left Outer Join

A left outer join, like this:

SELECT *
FROM `t1`
LEFT OUTER JOIN `t2` ON `t1`.`id` = `t2`.`id`;

...would get us all the records from the left table regardless of whether or not they have a match in the right table, like this:

1 Tim   1    Tim
2 Marta NULL NULL

Right Outer Join

A right outer join, like this:

SELECT *
FROM `t1`
RIGHT OUTER JOIN `t2` ON `t1`.`id` = `t2`.`id`;

...would get us all the records from the right table regardless of whether or not they have a match in the left table, like this:

1    Tim   1  Tim
NULL NULL  3  Katarina

Full Outer Join

A full outer join would give us all records from both tables, whether or not they have a match in the other table, with NULLs on both sides where there is no match. The result would look like this:

1    Tim   1    Tim
2    Marta NULL NULL
NULL NULL  3    Katarina

However, as Pablo Santa Cruz pointed out, MySQL doesn't support this. We can emulate it by doing a UNION of a left join and a right join, like this:

SELECT *
FROM `t1`
LEFT OUTER JOIN `t2` ON `t1`.`id` = `t2`.`id`

UNION

SELECT *
FROM `t1`
RIGHT OUTER JOIN `t2` ON `t1`.`id` = `t2`.`id`;

You can think of a UNION as meaning "run both of these queries, then stack the results on top of each other"; some of the rows will come from the first query and some from the second.

It should be noted that a UNION in MySQL will eliminate exact duplicates: Tim would appear in both of the queries here, but the result of the UNION only lists him once. My database guru colleague feels that this behavior should not be relied upon. So to be more explicit about it, we could add a WHERE clause to the second query:

SELECT *
FROM `t1`
LEFT OUTER JOIN `t2` ON `t1`.`id` = `t2`.`id`

UNION

SELECT *
FROM `t1`
RIGHT OUTER JOIN `t2` ON `t1`.`id` = `t2`.`id`
WHERE `t1`.`id` IS NULL;

On the other hand, if you wanted to see duplicates for some reason, you could use UNION ALL.

Reading an image file into bitmap from sdcard, why am I getting a NullPointerException?

Try this code:

Bitmap bitmap = null;
File f = new File(_path);
BitmapFactory.Options options = new BitmapFactory.Options();
options.inPreferredConfig = Bitmap.Config.ARGB_8888;
try {
    bitmap = BitmapFactory.decodeStream(new FileInputStream(f), null, options);
} catch (FileNotFoundException e) {
    e.printStackTrace();
}         
image.setImageBitmap(bitmap);

No plot window in matplotlib

pylab.show() works but blocks (you need to close the window).

A much more convenient solution is to do pylab.ion() (interactive mode on) when you start: all (the pylab equivalents of) pyplot.* commands display their plot immediately. More information on the interactive mode can be found on the official web site.

I also second using the even more convenient ipython -pylab (--pylab, in newer versions), which allows you to skip the from … import … part (%pylab works, too, in newer IPython versions).

Should I use JSLint or JSHint JavaScript validation?

tl;dr takeaway:

If you're looking for a very high standard for yourself or team, JSLint. But its not necessarily THE standard, just A standard, some of which comes to us dogmatically from a javascript god named Doug Crockford. If you want to be a bit more flexible, or have some old pros on your team that don't buy into JSLint's opinions, or are going back and forth between JS and other C-family languages on a regular basis, try JSHint.

long version:

The reasoning behind the fork explains pretty well why JSHint exists:

http://badassjs.com/post/3364925033/jshint-an-community-driven-fork-of-jslint http://anton.kovalyov.net/2011/02/20/why-i-forked-jslint-to-jshint/

So I guess the idea is that it's "community-driven" rather than Crockford-driven. In practicality, JSHint is generally a bit more lenient (or at least configurable or agnostic) on a few stylistic and minor syntactical "opinions" that JSLint is a stickler on.

As an example, if you think both the A and B below are fine, or if you want to write code with one or more of the aspects of A that aren't available in B, JSHint is for you. If you think B is the only correct option... JSLint. I'm sure there are other differences, but this highlights a few.

A) Passes JSHint out of the box - fails JSLint

(function() {
  "use strict";
  var x=0, y=2;
  function add(val1, val2){
    return val1 + val2;
  }
  var z;
  for (var i=0; i<2; i++){
    z = add(y, x+i);
  }
})();

B) Passes Both JSHint and JSLint

(function () {
    "use strict";
    var x = 0, y = 2, i, z;
    function add(val1, val2) {
       return val1 + val2;
    }
    for (i = 0; i < 2; i += 1) {
        z = add(y, x + i);
    }
}());

Personally I find JSLint code very nice to look at, and the only hard features of it that I disagree with are its hatred of more than one var declaration in a function and of for-loop var i = 0 declarations, and some of the whitespace enforcements for function declarations.

A few of the whitespace things that JSLint enforces, I find to be not necessarily bad, but out of sync with some pretty standard whitespace conventions for other languages in the family (C, Java, Python, etc...), which are often followed as conventions in Javascript as well. Since I'm writing in various of these languages throughout the day, and working with team members who don't like Lint-style whitespace in our code, I find JSHint to be a good balance. It catches stuff that's a legitimate bug or really bad form, but doesn't bark at me like JSLint does (sometimes, in ways I can't disable) for the stylistic opinions or syntactic nitpicks that I don't care for.

A lot of good libraries aren't Lint'able, which to me demonstrates that there's some truth to the idea that some of JSLint is simply just about pushing 1 version of "good code" (which is, indeed, good code). But then again, the same libraries (or other good ones) probably aren't Hint'able either, so, touché.

C# constructors overloading

Maybe your class isn't quite complete. Personally, I use a private init() function with all of my overloaded constructors.

class Point2D {

  double X, Y;

  public Point2D(double x, double y) {
    init(x, y);
  }

  public Point2D(Point2D point) {
    if (point == null)
      throw new ArgumentNullException("point");
    init(point.X, point.Y);
  }

  void init(double x, double y) {
    // ... Contracts ...
    X = x;
    Y = y;
  }
}

Android Design Support Library expandable Floating Action Button(FAB) menu

  • First create the menu layouts in the your Activity layout xml file. For e.g. a linear layout with horizontal orientation and include a TextView for label then a Floating Action Button beside the TextView.

  • Create the menu layouts as per your need and number.

  • Create a Base Floating Action Button and on its click of that change the visibility of the Menu Layouts.

Please check the below code for the reference and for more info checkout my project from github

Checkout project from Github

<android.support.constraint.ConstraintLayout
            android:id="@+id/activity_main"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context="com.app.fabmenu.MainActivity">

            <android.support.design.widget.FloatingActionButton
                android:id="@+id/baseFloatingActionButton"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="16dp"
                android:layout_marginEnd="16dp"
                android:layout_marginRight="16dp"
                android:clickable="true"
                android:onClick="@{FabHandler::onBaseFabClick}"
                android:tint="@android:color/white"
                app:fabSize="normal"
                app:layout_constraintBottom_toBottomOf="@+id/activity_main"
                app:layout_constraintRight_toRightOf="@+id/activity_main"
                app:srcCompat="@drawable/ic_add_black_24dp" />

            <LinearLayout
                android:id="@+id/shareLayout"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="12dp"
                android:layout_marginEnd="24dp"
                android:layout_marginRight="24dp"
                android:gravity="center_vertical"
                android:orientation="horizontal"
                android:visibility="invisible"
                app:layout_constraintBottom_toTopOf="@+id/createLayout"
                app:layout_constraintLeft_toLeftOf="@+id/createLayout"
                app:layout_constraintRight_toRightOf="@+id/activity_main">

                <TextView
                    android:id="@+id/shareLabelTextView"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginEnd="8dp"
                    android:layout_marginRight="8dp"
                    android:background="@drawable/shape_fab_label"
                    android:elevation="2dp"
                    android:fontFamily="sans-serif"
                    android:padding="5dip"
                    android:text="Share"
                    android:textColor="@android:color/white"
                    android:typeface="normal" />


                <android.support.design.widget.FloatingActionButton
                    android:id="@+id/shareFab"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:clickable="true"
                    android:onClick="@{FabHandler::onShareFabClick}"
                    android:tint="@android:color/white"
                    app:fabSize="mini"
                    app:srcCompat="@drawable/ic_share_black_24dp" />

            </LinearLayout>

            <LinearLayout
                android:id="@+id/createLayout"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="24dp"
                android:layout_marginEnd="24dp"
                android:layout_marginRight="24dp"
                android:gravity="center_vertical"
                android:orientation="horizontal"
                android:visibility="invisible"
                app:layout_constraintBottom_toTopOf="@+id/baseFloatingActionButton"
                app:layout_constraintRight_toRightOf="@+id/activity_main">

                <TextView
                    android:id="@+id/createLabelTextView"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginEnd="8dp"
                    android:layout_marginRight="8dp"
                    android:background="@drawable/shape_fab_label"
                    android:elevation="2dp"
                    android:fontFamily="sans-serif"
                    android:padding="5dip"
                    android:text="Create"
                    android:textColor="@android:color/white"
                    android:typeface="normal" />

                <android.support.design.widget.FloatingActionButton
                    android:id="@+id/createFab"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:clickable="true"
                    android:onClick="@{FabHandler::onCreateFabClick}"
                    android:tint="@android:color/white"
                    app:fabSize="mini"
                    app:srcCompat="@drawable/ic_create_black_24dp" />

            </LinearLayout>

        </android.support.constraint.ConstraintLayout>

These are the animations-

Opening animation of FAB Menu:

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:fillAfter="true">
<scale
    android:duration="300"
    android:fromXScale="0"
    android:fromYScale="0"
    android:interpolator="@android:anim/linear_interpolator"
    android:pivotX="50%"
    android:pivotY="50%"
    android:toXScale="1"
    android:toYScale="1" />
<alpha
    android:duration="300"
    android:fromAlpha="0.0"
    android:interpolator="@android:anim/accelerate_interpolator"
    android:toAlpha="1.0" />

</set>

Closing animation of FAB Menu:

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:fillAfter="true">
<scale
    android:duration="300"
    android:fromXScale="1"
    android:fromYScale="1"
    android:interpolator="@android:anim/linear_interpolator"
    android:pivotX="50%"
    android:pivotY="50%"
    android:toXScale="0.0"
    android:toYScale="0.0" />
<alpha
    android:duration="300"
    android:fromAlpha="1.0"
    android:interpolator="@android:anim/accelerate_interpolator"
    android:toAlpha="0.0" />
</set>

Then in my Activity I've simply used the animations above to show and hide the FAB menu :

Show Fab Menu:

  private void expandFabMenu() {

    ViewCompat.animate(binding.baseFloatingActionButton).rotation(45.0F).withLayer().setDuration(300).setInterpolator(new OvershootInterpolator(10.0F)).start();
    binding.createLayout.startAnimation(fabOpenAnimation);
    binding.shareLayout.startAnimation(fabOpenAnimation);
    binding.createFab.setClickable(true);
    binding.shareFab.setClickable(true);
    isFabMenuOpen = true;

}

Close Fab Menu:

private void collapseFabMenu() {

    ViewCompat.animate(binding.baseFloatingActionButton).rotation(0.0F).withLayer().setDuration(300).setInterpolator(new OvershootInterpolator(10.0F)).start();
    binding.createLayout.startAnimation(fabCloseAnimation);
    binding.shareLayout.startAnimation(fabCloseAnimation);
    binding.createFab.setClickable(false);
    binding.shareFab.setClickable(false);
    isFabMenuOpen = false;

}

Here is the the Activity class -

package com.app.fabmenu;

import android.databinding.DataBindingUtil;
import android.os.Bundle;
import android.support.design.widget.Snackbar;
import android.support.v4.view.ViewCompat;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.OvershootInterpolator;

import com.app.fabmenu.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity {

private ActivityMainBinding binding;
private Animation fabOpenAnimation;
private Animation fabCloseAnimation;
private boolean isFabMenuOpen = false;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    binding = DataBindingUtil.setContentView(this,    R.layout.activity_main);
    binding.setFabHandler(new FabHandler());

    getAnimations();


}

private void getAnimations() {

    fabOpenAnimation = AnimationUtils.loadAnimation(this, R.anim.fab_open);

    fabCloseAnimation = AnimationUtils.loadAnimation(this, R.anim.fab_close);

}

private void expandFabMenu() {

    ViewCompat.animate(binding.baseFloatingActionButton).rotation(45.0F).withLayer().setDuration(300).setInterpolator(new OvershootInterpolator(10.0F)).start();
    binding.createLayout.startAnimation(fabOpenAnimation);
    binding.shareLayout.startAnimation(fabOpenAnimation);
    binding.createFab.setClickable(true);
    binding.shareFab.setClickable(true);
    isFabMenuOpen = true;


}

private void collapseFabMenu() {

    ViewCompat.animate(binding.baseFloatingActionButton).rotation(0.0F).withLayer().setDuration(300).setInterpolator(new OvershootInterpolator(10.0F)).start();
    binding.createLayout.startAnimation(fabCloseAnimation);
    binding.shareLayout.startAnimation(fabCloseAnimation);
    binding.createFab.setClickable(false);
    binding.shareFab.setClickable(false);
    isFabMenuOpen = false;

}


public class FabHandler {

    public void onBaseFabClick(View view) {

        if (isFabMenuOpen)
            collapseFabMenu();
        else
            expandFabMenu();


    }

    public void onCreateFabClick(View view) {

        Snackbar.make(binding.coordinatorLayout, "Create FAB tapped", Snackbar.LENGTH_SHORT).show();

    }

    public void onShareFabClick(View view) {

        Snackbar.make(binding.coordinatorLayout, "Share FAB tapped", Snackbar.LENGTH_SHORT).show();

    }


}

@Override
public void onBackPressed() {

    if (isFabMenuOpen)
        collapseFabMenu();
    else
        super.onBackPressed();
}
}

Here are the screenshots

Floating Action Menu with Label Textview in new Cursive Font Family of Android

Floating Action Menu with Label Textview in new Roboto Font Family of Android

Mysql select distinct

DISTINCT is not a function that applies only to some columns. It's a query modifier that applies to all columns in the select-list.

That is, DISTINCT reduces rows only if all columns are identical to the columns of another row.

DISTINCT must follow immediately after SELECT (along with other query modifiers, like SQL_CALC_FOUND_ROWS). Then following the query modifiers, you can list columns.

  • RIGHT: SELECT DISTINCT foo, ticket_id FROM table...

    Output a row for each distinct pairing of values across ticket_id and foo.

  • WRONG: SELECT foo, DISTINCT ticket_id FROM table...

    If there are three distinct values of ticket_id, would this return only three rows? What if there are six distinct values of foo? Which three values of the six possible values of foo should be output?
    It's ambiguous as written.

Why doesn't calling a Python string method do anything unless you assign its output?

Example for String Methods

Given a list of filenames, we want to rename all the files with extension hpp to the extension h. To do this, we would like to generate a new list called newfilenames, consisting of the new filenames. Fill in the blanks in the code using any of the methods you’ve learned thus far, like a for loop or a list comprehension.

filenames = ["program.c", "stdio.hpp", "sample.hpp", "a.out", "math.hpp", "hpp.out"]
# Generate newfilenames as a list containing the new filenames
# using as many lines of code as your chosen method requires.
newfilenames = []
for i in filenames:
    if i.endswith(".hpp"):
        x = i.replace("hpp", "h")
        newfilenames.append(x)
    else:
        newfilenames.append(i)


print(newfilenames)
# Should be ["program.c", "stdio.h", "sample.h", "a.out", "math.h", "hpp.out"]

python max function using 'key' and lambda expression

max is built in function which takes first argument an iterable (like list or tuple)

keyword argument key has it's default value None but it accept function to evaluate, consider it as wrapper which evaluates iterable based on function

Consider this example dictionary:

d = {'aim':99, 'aid': 45, 'axe': 59, 'big': 9, 'short': 995, 'sin':12, 'sword':1, 'friend':1000, 'artwork':23}

Ex:

>>> max(d.keys())
'sword'

As you can see if you only pass the iterable without kwarg(a function to key) it is returning maximum value of key(alphabetically)

Ex. Instead of finding max value of key alphabetically you might need to find max key by length of key:

>>>max(d.keys(), key=lambda x: len(x))
'artwork'

in this example lambda function is returning length of key which will be iterated hence while evaluating values instead of considering alphabetically it will keep track of max length of key and returns key which has max length

Ex.

>>> max(d.keys(), key=lambda x: d[x])
'friend'

in this example lambda function is returning value of corresponding dictionary key which has maximum value

How do I get the coordinates of a mouse click on a canvas element?

Here is some modifications of the above Ryan Artecona's solution.

function myGetPxStyle(e,p)
{
    var r=window.getComputedStyle?window.getComputedStyle(e,null)[p]:"";
    return parseFloat(r);
}

function myGetClick=function(ev)
{
    // {x:ev.layerX,y:ev.layerY} doesn't work when zooming with mac chrome 27
    // {x:ev.clientX,y:ev.clientY} not supported by mac firefox 21
    // document.body.scrollLeft and document.body.scrollTop seem required when scrolling on iPad
    // html is not an offsetParent of body but can have non null offsetX or offsetY (case of wordpress 3.5.1 admin pages for instance)
    // html.offsetX and html.offsetY don't work with mac firefox 21

    var offsetX=0,offsetY=0,e=this,x,y;
    var htmls=document.getElementsByTagName("html"),html=(htmls?htmls[0]:0);

    do
    {
        offsetX+=e.offsetLeft-e.scrollLeft;
        offsetY+=e.offsetTop-e.scrollTop;
    } while (e=e.offsetParent);

    if (html)
    {
        offsetX+=myGetPxStyle(html,"marginLeft");
        offsetY+=myGetPxStyle(html,"marginTop");
    }

    x=ev.pageX-offsetX-document.body.scrollLeft;
    y=ev.pageY-offsetY-document.body.scrollTop;
    return {x:x,y:y};
}

Stored procedure return into DataSet in C# .Net

I should tell you the basic steps and rest depends upon your own effort. You need to perform following steps.

  • Create a connection string.
  • Create a SQL connection
  • Create SQL command
  • Create SQL data adapter
  • fill your dataset.

Do not forget to open and close connection. follow this link for more under standing.

Java 8 stream's .min() and .max(): why does this compile?

Apart from the information given by David M. Lloyd one could add that the mechanism that allows this is called target typing.

The idea is that the type the compiler assigns to a lambda expressions or a method references does not depend only on the expression itself, but also on where it is used.

The target of an expression is the variable to which its result is assigned or the parameter to which its result is passed.

Lambda expressions and method references are assigned a type which matches the type of their target, if such a type can be found.

See the Type Inference section in the Java Tutorial for more information.

Why doesn't C++ have a garbage collector?

tl;dr: Because modern C++ doesn't need garbage collection.

Bjarne Stroustrup's FAQ answer on this matter says:

I don't like garbage. I don't like littering. My ideal is to eliminate the need for a garbage collector by not producing any garbage. That is now possible.


The situation, for code written these days (C++17 and following the official Core Guidelines) is as follows:

  • Most memory ownership-related code is in libraries (especially those providing containers).
  • Most use of code involving memory ownership follows the RAII pattern, so allocation is made on construction and deallocation on destruction, which happens when exiting the scope in which something was allocated.
  • You do not explicitly allocate or deallocate memory directly.
  • Raw pointers do not own memory (if you've followed the guidelines), so you can't leak by passing them around.
  • If you're wondering how you're going to pass the starting addresses of sequences of values in memory - you'll be doing that with a span; no raw pointer needed.
  • If you really need an owning "pointer", you use C++' standard-library smart pointers - they can't leak, and are decently efficient (although the ABI can get in the way of that). Alternatively, you can pass ownership across scope boundaries with "owner pointers". These are uncommon and must be used explicitly; but when adopted - they allow for nice static checking against leaks.

"Oh yeah? But what about...

... if I just write code the way we used to write C++ in the old days?"

Indeed, you could just disregard all of the guidelines and write leaky application code - and it will compile and run (and leak), same as always.

But it's not a "just don't do that" situation, where the developer is expected to be virtuous and exercise a lot of self control; it's just not simpler to write non-conforming code, nor is it faster to write, nor is it better-performing. Gradually it will also become more difficult to write, as you would face an increasing "impedance mismatch" with what conforming code provides and expects.

... if I reintrepret_cast? Or do complex pointer arithmetic? Or other such hacks?"

Indeed, if you put your mind to it, you can write code that messes things up despite playing nice with the guidelines. But:

  1. You would do this rarely (in terms of places in the code, not necessarily in terms of fraction of execution time)
  2. You would only do this intentionally, not accidentally.
  3. Doing so will stand out in a codebase conforming to the guidelines.
  4. It's the kind of code in which you would bypass the GC in another language anyway.

... library development?"

If you're a C++ library developer then you do write unsafe code involving raw pointers, and you are required to code carefully and responsibly - but these are self-contained pieces of code written by experts (and more importantly, reviewed by experts).


So, it's just like Bjarne said: There's really no motivation to collect garbage generally, as you all but make sure not to produce garbage. GC is becoming a non-problem with C++.

That is not to say GC isn't an interesting problem for certain specific applications, when you want to employ custom allocation and de-allocations strategies. For those you would want custom allocation and de-allocation, not a language-level GC.

What's the best mock framework for Java?

We are heavily using EasyMock and EasyMock Class Extension at work and are pretty happy with it. It basically gives you everything you need. Take a look at the documentation, there's a very nice example which shows you all the features of EasyMock.

Creating a Shopping Cart using only HTML/JavaScript

Here's a one page cart written in Javascript with localStorage. Here's a full working pen. Previously found on Codebox

cart.js

var cart = {
  // (A) PROPERTIES
  hPdt : null, // HTML products list
  hItems : null, // HTML current cart
  items : {}, // Current items in cart

  // (B) LOCALSTORAGE CART
  // (B1) SAVE CURRENT CART INTO LOCALSTORAGE
  save : function () {
    localStorage.setItem("cart", JSON.stringify(cart.items));
  },

  // (B2) LOAD CART FROM LOCALSTORAGE
  load : function () {
    cart.items = localStorage.getItem("cart");
    if (cart.items == null) { cart.items = {}; }
    else { cart.items = JSON.parse(cart.items); }
  },

  // (B3) EMPTY ENTIRE CART
  nuke : function () {
    if (confirm("Empty cart?")) {
      cart.items = {};
      localStorage.removeItem("cart");
      cart.list();
    }
  },

  // (C) INITIALIZE
  init : function () {
    // (C1) GET HTML ELEMENTS
    cart.hPdt = document.getElementById("cart-products");
    cart.hItems = document.getElementById("cart-items");

    // (C2) DRAW PRODUCTS LIST
    cart.hPdt.innerHTML = "";
    let p, item, part;
    for (let id in products) {
      // WRAPPER
      p = products[id];
      item = document.createElement("div");
      item.className = "p-item";
      cart.hPdt.appendChild(item);

      // PRODUCT IMAGE
      part = document.createElement("img");
      part.src = "images/" +p.img;
      part.className = "p-img";
      item.appendChild(part);

      // PRODUCT NAME
      part = document.createElement("div");
      part.innerHTML = p.name;
      part.className = "p-name";
      item.appendChild(part);

      // PRODUCT DESCRIPTION
      part = document.createElement("div");
      part.innerHTML = p.desc;
      part.className = "p-desc";
      item.appendChild(part);

      // PRODUCT PRICE
      part = document.createElement("div");
      part.innerHTML = "$" + p.price;
      part.className = "p-price";
      item.appendChild(part);

      // ADD TO CART
      part = document.createElement("input");
      part.type = "button";
      part.value = "Add to Cart";
      part.className = "cart p-add";
      part.onclick = cart.add;
      part.dataset.id = id;
      item.appendChild(part);
    }

    // (C3) LOAD CART FROM PREVIOUS SESSION
    cart.load();

    // (C4) LIST CURRENT CART ITEMS
    cart.list();
  },

  // (D) LIST CURRENT CART ITEMS (IN HTML)
  list : function () {
    // (D1) RESET
    cart.hItems.innerHTML = "";
    let item, part, pdt;
    let empty = true;
    for (let key in cart.items) {
      if(cart.items.hasOwnProperty(key)) { empty = false; break; }
    }

    // (D2) CART IS EMPTY
    if (empty) {
      item = document.createElement("div");
      item.innerHTML = "Cart is empty";
      cart.hItems.appendChild(item);
    }

    // (D3) CART IS NOT EMPTY - LIST ITEMS
    else {
      let p, total = 0, subtotal = 0;
      for (let id in cart.items) {
        // ITEM
        p = products[id];
        item = document.createElement("div");
        item.className = "c-item";
        cart.hItems.appendChild(item);

        // NAME
        part = document.createElement("div");
        part.innerHTML = p.name;
        part.className = "c-name";
        item.appendChild(part);

        // REMOVE
        part = document.createElement("input");
        part.type = "button";
        part.value = "X";
        part.dataset.id = id;
        part.className = "c-del cart";
        part.addEventListener("click", cart.remove);
        item.appendChild(part);

        // QUANTITY
        part = document.createElement("input");
        part.type = "number";
        part.value = cart.items[id];
        part.dataset.id = id;
        part.className = "c-qty";
        part.addEventListener("change", cart.change);
        item.appendChild(part);

        // SUBTOTAL
        subtotal = cart.items[id] * p.price;
        total += subtotal;
      }

      // EMPTY BUTTONS
      item = document.createElement("input");
      item.type = "button";
      item.value = "Empty";
      item.addEventListener("click", cart.nuke);
      item.className = "c-empty cart";
      cart.hItems.appendChild(item);

      // CHECKOUT BUTTONS
      item = document.createElement("input");
      item.type = "button";
      item.value = "Checkout - " + "$" + total;
      item.addEventListener("click", cart.checkout);
      item.className = "c-checkout cart";
      cart.hItems.appendChild(item);
    }
  },

  // (E) ADD ITEM INTO CART
  add : function () {
    if (cart.items[this.dataset.id] == undefined) {
      cart.items[this.dataset.id] = 1;
    } else {
      cart.items[this.dataset.id]++;
    }
    cart.save();
    cart.list();
  },

  // (F) CHANGE QUANTITY
  change : function () {
    if (this.value == 0) {
      delete cart.items[this.dataset.id];
    } else {
      cart.items[this.dataset.id] = this.value;
    }
    cart.save();
    cart.list();
  },
  
  // (G) REMOVE ITEM FROM CART
  remove : function () {
    delete cart.items[this.dataset.id];
    cart.save();
    cart.list();
  },
  
  // (H) CHECKOUT
  checkout : function () {
    // SEND DATA TO SERVER
    // CHECKS
    // SEND AN EMAIL
    // RECORD TO DATABASE
    // PAYMENT
    // WHATEVER IS REQUIRED
    alert("TO DO");

    /*
    var data = new FormData();
    data.append('cart', JSON.stringify(cart.items));
    data.append('products', JSON.stringify(products));
    var xhr = new XMLHttpRequest();
    xhr.open("POST", "SERVER-SCRIPT");
    xhr.onload = function(){ ... };
    xhr.send(data);
    */
  }
};
window.addEventListener("DOMContentLoaded", cart.init);

How to show data in a table by using psql command line interface?

On windows use the name of the table in quotes: TABLE "user"; or SELECT * FROM "user";

Handling the window closing event with WPF / MVVM Light Toolkit

private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
    {
        MessageBox.Show("closing");
    }

How to convert CLOB to VARCHAR2 inside oracle pl/sql

This is my aproximation:

  Declare 
  Variableclob Clob;
  Temp_Save Varchar2(32767); //whether it is greater than 4000

  Begin
  Select reportClob Into Temp_Save From Reporte Where Id=...;
  Variableclob:=To_Clob(Temp_Save);
  Dbms_Output.Put_Line(Variableclob);


  End;

PHP Get name of current directory

getcwd();

or

dirname(__FILE__);

or (PHP5)

basename(__DIR__) 

http://php.net/manual/en/function.getcwd.php

http://php.net/manual/en/function.dirname.php

You can use basename() to get the trailing part of the path :)

In your case, I'd say you are most likely looking to use getcwd(), dirname(__FILE__) is more useful when you have a file that needs to include another library and is included in another library.

Eg:

main.php
libs/common.php
libs/images/editor.php

In your common.php you need to use functions in editor.php, so you use

common.php:

require_once dirname(__FILE__) . '/images/editor.php';

main.php:

require_once libs/common.php

That way when common.php is require'd in main.php, the call of require_once in common.php will correctly includes editor.php in images/editor.php instead of trying to look in current directory where main.php is run.

Java socket API: How to tell if a connection has been closed?

There is no TCP API that will tell you the current state of the connection. isConnected() and isClosed() tell you the current state of your socket. Not the same thing.

  1. isConnected() tells you whether you have connected this socket. You have, so it returns true.

  2. isClosed() tells you whether you have closed this socket. Until you have, it returns false.

  3. If the peer has closed the connection in an orderly way

    • read() returns -1
    • readLine() returns null
    • readXXX() throws EOFException for any other XXX.

    • A write will throw an IOException: 'connection reset by peer', eventually, subject to buffering delays.

  4. If the connection has dropped for any other reason, a write will throw an IOException, eventually, as above, and a read may do the same thing.

  5. If the peer is still connected but not using the connection, a read timeout can be used.

  6. Contrary to what you may read elsewhere, ClosedChannelException doesn't tell you this. [Neither does SocketException: socket closed.] It only tells you that you closed the channel, and then continued to use it. In other words, a programming error on your part. It does not indicate a closed connection.

  7. As a result of some experiments with Java 7 on Windows XP it also appears that if:

    • you're selecting on OP_READ
    • select() returns a value of greater than zero
    • the associated SelectionKey is already invalid (key.isValid() == false)

    it means the peer has reset the connection. However this may be peculiar to either the JRE version or platform.

How do I make a dictionary with multiple keys to one value?

I guess you mean this:

class Value:
    def __init__(self, v=None):
        self.v = v

v1 = Value(1)
v2 = Value(2)

d = {'a': v1, 'b': v1, 'c': v2, 'd': v2}
d['a'].v += 1

d['b'].v == 2 # True
  • Python's strings and numbers are immutable objects,
  • So, if you want d['a'] and d['b'] to point to the same value that "updates" as it changes, make the value refer to a mutable object (user-defined class like above, or a dict, list, set).
  • Then, when you modify the object at d['a'], d['b'] changes at same time because they both point to same object.

How to return rows from left table not found in right table?

Try This

SELECT f.*
FROM first_table f LEFT JOIN second_table s ON f.key=s.key
WHERE s.key is NULL

For more please read this article : Joins in Sql Server

enter image description here

How can I remove Nan from list Python/NumPy

Another way to do it would include using filter like this:

countries = list(filter(lambda x: str(x) != 'nan', countries))

What is the use of join() in Python threading?

With join - interpreter will wait until your process get completed or terminated

>>> from threading import Thread
>>> import time
>>> def sam():
...   print 'started'
...   time.sleep(10)
...   print 'waiting for 10sec'
... 
>>> t = Thread(target=sam)
>>> t.start()
started

>>> t.join() # with join interpreter will wait until your process get completed or terminated
done?   # this line printed after thread execution stopped i.e after 10sec
waiting for 10sec
>>> done?

without join - interpreter wont wait until process get terminated,

>>> t = Thread(target=sam)
>>> t.start()
started
>>> print 'yes done' #without join interpreter wont wait until process get terminated
yes done
>>> waiting for 10sec

Number of days in particular month of particular year?

// 1 means Sunday ,2 means Monday .... 7 means Saturday
//month starts with 0 (January)

MonthDisplayHelper monthDisplayHelper = new MonthDisplayHelper(2019,4);
int numbeOfDaysInMonth = monthDisplayHelper.getNumberOfDaysInMonth();

Using Jquery AJAX function with datatype HTML

var datos = $("#id_formulario").serialize();
$.ajax({         
    url: "url.php",      
    type: "POST",                   
    dataType: "html",                 
    data: datos,                 
    success: function (prueba) { 
        alert("funciona!");
    }//FIN SUCCES

});//FIN  AJAX

How to set the thumbnail image on HTML5 video?

That seems to be an extra image being shown there.

You can try using this

<img src="/images/image_of_video.png" alt="image" />
/* write your code for the video here */

Now using jQuery play the video and hide the image as

$('img').click(function () {
  $(this).hide();
  // use the parameters to play the video now..
})

How to remove the last element added into the List?

I think the most efficient way to do this is this is using RemoveAt:

rows.RemoveAt(rows.Count - 1)

How to overwrite files with Copy-Item in PowerShell

As I understand Copy-Item -Exclude then you are doing it correct. What I usually do, get 1'st, and then do after, so what about using Get-Item as in

Get-Item -Path $copyAdmin -Exclude $exclude |
Copy-Item  -Path $copyAdmin -Destination $AdminPath -Recurse -force

How to while loop until the end of a file in Python without checking for empty line?

Don't loop through a file this way. Instead use a for loop.

for line in f:
    vowel += sum(ch.isvowel() for ch in line)

In fact your whole program is just:

VOWELS = {'A','E','I','O','U','a','e','i','o','u'}
# I'm assuming this is what isvowel checks, unless you're doing something
# fancy to check if 'y' is a vowel
with open('filename.txt') as f:
    vowel = sum(ch in VOWELS for line in f for ch in line.strip())

That said, if you really want to keep using a while loop for some misguided reason:

while True:
    line = f.readline().strip()
    if line == '':
        # either end of file or just a blank line.....
        # we'll assume EOF, because we don't have a choice with the while loop!
        break

SQL TRUNCATE DATABASE ? How to TRUNCATE ALL TABLES

The accepted answer doesn't quite work when you have foreign key relationships. In that case you have to drop the constraints and recreate them. Below is a stored proc for doing that based on the answer here

CREATE PROCEDURE [dbo].[deleteAllDataFromAllTables] AS
SET NOCOUNT ON

    DECLARE @dropAndCreateConstraintsTable TABLE ( DropStmt varchar(max) , CreateStmt varchar(max) )

    insert @dropAndCreateConstraintsTable select
      DropStmt = 'ALTER TABLE [' + ForeignKeys.ForeignTableSchema + 
          '].[' + ForeignKeys.ForeignTableName + 
          '] DROP CONSTRAINT [' + ForeignKeys.ForeignKeyName + ']; '
    ,  CreateStmt = 'ALTER TABLE [' + ForeignKeys.ForeignTableSchema + 
          '].[' + ForeignKeys.ForeignTableName + 
          '] WITH CHECK ADD CONSTRAINT [' +  ForeignKeys.ForeignKeyName + 
          '] FOREIGN KEY([' + ForeignKeys.ForeignTableColumn + 
          ']) REFERENCES [' + schema_name(sys.objects.schema_id) + '].[' +
      sys.objects.[name] + ']([' +
      sys.columns.[name] + ']); '
     from sys.objects
      inner join sys.columns
        on (sys.columns.[object_id] = sys.objects.[object_id])
      inner join (
        select sys.foreign_keys.[name] as ForeignKeyName
         ,schema_name(sys.objects.schema_id) as ForeignTableSchema
         ,sys.objects.[name] as ForeignTableName
         ,sys.columns.[name]  as ForeignTableColumn
         ,sys.foreign_keys.referenced_object_id as referenced_object_id
         ,sys.foreign_key_columns.referenced_column_id as referenced_column_id
         from sys.foreign_keys
          inner join sys.foreign_key_columns
            on (sys.foreign_key_columns.constraint_object_id
              = sys.foreign_keys.[object_id])
          inner join sys.objects
            on (sys.objects.[object_id]
              = sys.foreign_keys.parent_object_id)
            inner join sys.columns
              on (sys.columns.[object_id]
                = sys.objects.[object_id])
               and (sys.columns.column_id
                = sys.foreign_key_columns.parent_column_id)
        ) ForeignKeys
        on (ForeignKeys.referenced_object_id = sys.objects.[object_id])
         and (ForeignKeys.referenced_column_id = sys.columns.column_id)
     where (sys.objects.[type] = 'U')
      and (sys.objects.[name] not in ('sysdiagrams'))


    DECLARE @DropStatement nvarchar(max)
    DECLARE @RecreateStatement nvarchar(max)

    DECLARE C1 CURSOR READ_ONLY
    FOR
    SELECT DropStmt from @dropAndCreateConstraintsTable
    OPEN C1

    FETCH NEXT FROM C1 INTO @DropStatement

    WHILE @@FETCH_STATUS = 0
    BEGIN
        PRINT 'Executing ' + @DropStatement
        execute sp_executesql @DropStatement
        FETCH NEXT FROM C1 INTO @DropStatement
    END
    CLOSE C1
    DEALLOCATE C1

    DECLARE @DeleteTableStatement nvarchar(max)
    DECLARE C2 CURSOR READ_ONLY
    FOR
    SELECT 'Delete From [dbo].[' + TABLE_NAME + ']' from INFORMATION_SCHEMA.TABLES 
        WHERE TABLE_SCHEMA = 'dbo' -- Change your schema appropriately.
    OPEN C2

    FETCH NEXT FROM C2 INTO @DeleteTableStatement

    WHILE @@FETCH_STATUS = 0
    BEGIN
        PRINT 'Executing ' + @DeleteTableStatement
        execute sp_executesql @DeleteTableStatement
        FETCH NEXT FROM C2 INTO  @DeleteTableStatement
    END
    CLOSE C2
    DEALLOCATE C2

    DECLARE C3 CURSOR READ_ONLY
    FOR
    SELECT CreateStmt from @dropAndCreateConstraintsTable
    OPEN C3

    FETCH NEXT FROM C3 INTO @RecreateStatement

    WHILE @@FETCH_STATUS = 0
    BEGIN
        PRINT 'Executing ' + @RecreateStatement
        execute sp_executesql @RecreateStatement
        FETCH NEXT FROM C3 INTO  @RecreateStatement
    END
    CLOSE C3
    DEALLOCATE C3

GO

How to use CMAKE_INSTALL_PREFIX

But do remember to place it BEFORE PROJECT(< project_name>) command, otherwise it will not work!

My first week of using cmake - after some years of GNU autotools - so I am still learning (better then writing m4 macros), but I think modifying CMAKE_INSTALL_PREFIX after setting project is the better place.

CMakeLists.txt

cmake_minimum_required (VERSION 2.8)

set (CMAKE_INSTALL_PREFIX /foo/bar/bubba)
message("CIP = ${CMAKE_INSTALL_PREFIX} (should be /foo/bar/bubba")
project (BarkBark)
message("CIP = ${CMAKE_INSTALL_PREFIX} (should be /foo/bar/bubba")
set (CMAKE_INSTALL_PREFIX /foo/bar/bubba)
message("CIP = ${CMAKE_INSTALL_PREFIX} (should be /foo/bar/bubba")

First run (no cache)

CIP = /foo/bar/bubba (should be /foo/bar/bubba
-- The C compiler identification is GNU 4.4.7
-- etc, etc,...
CIP = /usr/local (should be /foo/bar/bubba
CIP = /foo/bar/bubba (should be /foo/bar/bubba
-- Configuring done
-- Generating done

Second run

CIP = /foo/bar/bubba (should be /foo/bar/bubba
CIP = /foo/bar/bubba (should be /foo/bar/bubba
CIP = /foo/bar/bubba (should be /foo/bar/bubba
-- Configuring done
-- Generating done

Let me know if I am mistaken, I have a lot of learning to do. It's fun.

Loading PictureBox Image from resource file with path (Part 3)

Setting "Copy to Output Directory" to "Copy always" or "Copy if newer" may help for you.

Your PicPath is a relative path that is converted into an absolute path at some time while loading the image. Most probably you will see that there are no images on the specified location if you use Path.GetFullPath(PicPath) in Debug.

OpenCV Python rotate image by X degrees around specific point

Or much easier use SciPy

from scipy import ndimage

#rotation angle in degree
rotated = ndimage.rotate(image_to_rotate, 45)

see here for more usage info.

"Mixed content blocked" when running an HTTP AJAX operation in an HTTPS page

I was same problem, but for me the problem was ng build command. I was doing "ng build --prod" i have corrected it to "ng build --prod --base-href /applicationname/". and this solved my problem.

How to convert QString to std::string?

Try this:

#include <QDebug>
QString string;
// do things...
qDebug() << "right" << string << std::endl;

Predicate in Java

You can view the java doc examples or the example of usage of Predicate here

Basically it is used to filter rows in the resultset based on any specific criteria that you may have and return true for those rows that are meeting your criteria:

 // the age column to be between 7 and 10
    AgeFilter filter = new AgeFilter(7, 10, 3);

    // set the filter.
    resultset.beforeFirst();
    resultset.setFilter(filter);

Combining multiple condition in single case statement in Sql Server

You can put the condition after the WHEN clause, like so:

SELECT
  CASE
    WHEN PAT_ENT.SCR_DT is not null and PAT_ENTRY.ELIGIBILITY is null THEN 'Favor'
    WHEN PAT_ENT.SCR_DT is not null and PAT_ENTRY.EL = 'No' THEN 'Error'
    WHEN PAT_ENTRY.EL = 'Yes' and ISNULL(DS.DES, 'OFF') = 'OFF' THEN 'Active'
    WHEN DS.DES = 'N' THEN 'Early Term'
    WHEN DS.DES = 'Y' THEN 'Complete'
  END
FROM
  ....

Of course, the argument could be made that complex rules like this belong in your business logic layer, not in a stored procedure in the database...

jQuery: count number of rows in a table

I needed a way to do this in an AJAX return, so I wrote this piece:

<p id="num_results">Number of results: <span></span></p>

<div id="results"></div>

<script type="text/javascript">
$(function(){
    ajax();
})

//Function that makes Ajax call out to receive search results
var ajax = function() {
    //Setup Ajax
    $.ajax({
        url: '/path/to/url', //URL to load
        type: 'GET', //Type of Ajax call
        dataType: 'html', //Type of data to be expected on return
        success: function(data) { //Function that manipulates the returned AJAX'ed data
            $('#results').html(data); //Load the data into a HTML holder
            var $el = $('#results'); //jQuery Object that is holding the results
            setTimeout(function(){ //Custom callback function to count the number of results
                callBack($el);
            });
        }
    });
}

//Custom Callback function to return the number of results
var callBack = function(el) {
    var length = $('tr', $(el)).not('tr:first').length; //Count all TR DOM elements, except the first row (which contains the header information)
    $('#num_results span').text(length); //Write the counted results to the DOM
}
</script>

Obviously this is a quick example, but it may be helpful.

How to call base.base.method()?

As can be seen from previous posts, one can argue that if class functionality needs to be circumvented then something is wrong in the class architecture. That might be true, but one cannot always restructure or refactor the class structure on a large mature project. The various levels of change management might be one problem, but to keep existing functionality operating the same after refactoring is not always a trivial task, especially if time constraints apply. On a mature project it can be quite an undertaking to keep various regression tests from passing after a code restructure; there are often obscure "oddities" that show up. We had a similar problem in some cases inherited functionality should not execute (or should perform something else). The approach we followed below, was to put the base code that need to be excluded in a separate virtual function. This function can then be overridden in the derived class and the functionality excluded or altered. In this example "Text 2" can be prevented from output in the derived class.

public class Base
{
    public virtual void Foo()
    {
        Console.WriteLine("Hello from Base");
    }
}

public class Derived : Base
{
    public override void Foo()
    {
        base.Foo();
        Console.WriteLine("Text 1");
        WriteText2Func();
        Console.WriteLine("Text 3");
    }

    protected virtual void WriteText2Func()
    {  
        Console.WriteLine("Text 2");  
    }
}

public class Special : Derived
{
    public override void WriteText2Func()
    {
        //WriteText2Func will write nothing when 
        //method Foo is called from class Special.
        //Also it can be modified to do something else.
    }
}

WPF MVVM ComboBox SelectedItem or SelectedValue not working

You can also bind your SelectedIndex to a property in your ViewModel and manipulate your SelectedItem that way:

        public int SelectedIndex
        {
            get { return _selectedIndex; }
            set
            {
                _selectedIndex = value;
                OnPropertyChanged();
            }    
        }

And in your XAML:

<ComboBox SelectedIndex="{Binding SelectedIndex,Mode=TwoWay}" ... >

How do I validate a date string format in python?

I think the full validate function should look like this:

from datetime import datetime

def validate(date_text):
    try:
        if date_text != datetime.strptime(date_text, "%Y-%m-%d").strftime('%Y-%m-%d'):
            raise ValueError
        return True
    except ValueError:
        return False

Executing just

datetime.strptime(date_text, "%Y-%m-%d") 

is not enough because strptime method doesn't check that month and day of the month are zero-padded decimal numbers. For example

datetime.strptime("2016-5-3", '%Y-%m-%d')

will be executed without errors.

Makefile If-Then Else and Loops

Have you tried the GNU make documentation? It has a whole section about conditionals with examples.

How to echo print statements while executing a sql script

This will give you are simple print within a sql script:

select 'This is a comment' AS '';

Alternatively, this will add some dynamic data to your status update if used directly after an update, delete, or insert command:

select concat ("Updated ", row_count(), " rows") as ''; 

java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonFactory

You have to add one jar : jackson-annotations-2.1.2.jar You can download it from here and add it to the class path If you are using the gradle then add the following dependency.

compile 'com.fasterxml.jackson.jaxrs:jackson-jaxrs-json-provider:2.5.2'

NuGet auto package restore does not work with MSBuild

Note that if you are using TeamCity as a build server, you get a "NuGet Installer" step that you can use to restore all the packages before the build step.

powershell mouse move does not prevent idle mode

<# Stay Awake by Frank Poth 2019-04-16 #>

(Get-Host).UI.RawUI.WindowTitle = "Stay Awake"

[System.Console]::BufferWidth  = [System.Console]::WindowWidth  = 40
[System.Console]::BufferHeight = [System.Console]::WindowHeight = 10

$shell = New-Object -ComObject WScript.Shell

$start_time = Get-Date -UFormat %s <# Get the date in MS #>
$current_time = $start_time
$elapsed_time = 0

Write-Host "I am awake!"

Start-Sleep -Seconds 5

$count = 0

while($true) {

  $shell.sendkeys("{NUMLOCK}{NUMLOCK}") <# Fake some input! #>

  if ($count -eq 8) {

    $count = 0
    Clear-Host

  }

  if ($count -eq 0) {

    $current_time = Get-Date -UFormat %s
    $elapsed_time = $current_time - $start_time

    Write-Host "I've been awake for "([System.Math]::Round(($elapsed_time / 60), 2))" minutes!"

  } else { Write-Host "Must stay awake..." }

  $count ++

  Start-Sleep -Seconds 2.5

}

The part that matters is $shell.sendkeys("{NUMLOCK}{NUMLOCK}") This registers two presses on the numlock key and fools the shell into thinking input was entered. I wrote this today after searching through various scripts that didn't work for me. Hope it helps someone!

Get current domain

I know this might not be entirely on the subject, but in my experience, I find storing WWW-ness of current URL in a variable useful.

Edit: In addition, please see my comment below, to see what this is getting at.

This is important when determining whether to dispatch Ajax calls with "www", or without:

$.ajax("url" : "www.site.com/script.php", ...

$.ajax("url" : "site.com/script.php", ...

When dispatching an Ajax call the domain name must match that of in the browser's address bar, otherwise you will have Uncaught SecurityError in console.

So I came up with this solution to address the issue:

<?php
    substr($_SERVER['SERVER_NAME'], 0, 3) == "www" ? $WWW = true : $WWW = false;

    if ($WWW) {
        /* We have www.example.com */
    } else {
        /* We have example.com */
    }
?>

Then, based on whether $WWW is true, or false run the proper Ajax call.

I know this might sound trivial, but this is such a common problem that is easy to trip over.

Which command do I use to generate the build of a Vue app?

The vue documentation provides a lot of information on this on how you can deploy to different host providers.

npm run build

You can find this from the package json file. scripts section. It provides scripts for testing and development and building for production.

You can use services such as netlify which will bundle your project by linking up your github repo of the project from their site. It also provides information on how to deploy on other sites such as heroku.

You can find more details on this here

How can I send emails through SSL SMTP with the .NET Framework?

You can also connect via port 465, but due to some limitations of the System.Net.Mail namespace you may have to alter your code. This is because the namespace does not offer the ability to make implicit SSL connections. This is discussed at http://blogs.msdn.com/b/webdav_101/archive/2008/06/02/system-net-mail-with-ssl-to-authenticate-against-port-465.aspx.

It is possible to make implicit connections without having to use the now obsolete System.Web.Mail namespace, but you have to access the Microsoft CDO (Collaborative Data Object). I have supplied an example of how to use the CDO in another discussion (GMail SMTP via C# .Net errors on all ports).

Hope this helps!

How to add anything in <head> through jquery/javascript?

jQuery

$('head').append( ... );

JavaScript:

document.getElementsByTagName('head')[0].appendChild( ... );

font-weight is not working properly?

Its because the font size (9px) is too small to display bold. Try 11px or more and it works fine.

Checking if a character is a special character in Java

What I would do:

char c;
int cint;
for(int n = 0; n < str.length(); n ++;)
{
    c = str.charAt(n);
    cint = (int)c;
    if(cint <48 || (cint > 57 && cint < 65) || (cint > 90 && cint < 97) || cint > 122)
    {
        specialCharacterCount++
    }
}

That is a simple way to do things, without having to import any special classes. Stick it in a method, or put it straight into the main code.

ASCII chart: http://www.gophoto.it/view.php?i=http://i.msdn.microsoft.com/dynimg/IC102418.gif#.UHsqxFEmG08

C++ - unable to start correctly (0xc0150002)

Even I faced same error, I fixed it afterwards... Two things you need to look into

  1. Whether your system path is correctly set in your environment variables
  2. Check the pre-processors in Project Properties->c/c++->Pre-processors. Check whether you have included _CONSOLE, this was causing error for me. For Some applications you need to include WIN32;_WINDOWS;_CONSOLE;_DEBUG;QT_DLL;QT_GUI_LIB;QT_NETWORK_LIB;QT_CORE_LIB;COIN_DLL;SOQT_DLL;QT_DEBUG;

I got this error while I was working in coin3D Application.

DateTime.Compare how to check if a date is less than 30 days old?

You can try to do like this:

var daysPassed = (DateTime.UtcNow - expiryDate).Days;
if (daysPassed > 30)
{ 
    // ...
}

ESLint - "window" is not defined. How to allow global variables in package.json

I'm aware he's not asking for the inline version. But since this question has almost 100k visits and I fell here looking for that, I'll leave it here for the next fellow coder:

Make sure ESLint is not run with the --no-inline-config flag (if this doesn't sound familiar, you're likely good to go). Then, write this in your code file (for clarity and convention, it's written on top of the file but it'll work anywhere):

/* eslint-env browser */

This tells ESLint that your working environment is a browser, so now it knows what things are available in a browser and adapts accordingly.

There are plenty of environments, and you can declare more than one at the same time, for example, in-line:

/* eslint-env browser, node */

If you are almost always using particular environments, it's best to set it in your ESLint's config file and forget about it.

From their docs:

An environment defines global variables that are predefined. The available environments are:

  • browser - browser global variables.
  • node - Node.js global variables and Node.js scoping.
  • commonjs - CommonJS global variables and CommonJS scoping (use this for browser-only code that uses Browserify/WebPack).
  • shared-node-browser - Globals common to both Node and Browser.

[...]

Besides environments, you can make it ignore anything you want. If it warns you about using console.log() but you don't want to be warned about it, just inline:

/* eslint-disable no-console */

You can see the list of all rules, including recommended rules to have for best coding practices.

How to avoid soft keyboard pushing up my layout?

In my case, the reason the buttons got pushed up was because the view above them was a ScrollView, and it got collapsed with the buttons pushed up above the keyboard no matter what value of android:windowSoftInputMode I was setting.

I was able to avoid my bottom row of buttons getting pushed up by the soft keyboard by setting

android:isScrollContainer="false" 

on the ScrollView that sits above the buttons.

What possibilities can cause "Service Unavailable 503" error?

Your web pages are served by an application pool. If you disable/stop the application pool, and anyone tries to browse the application, you will get a Service Unavailable. It can happen due to multiple reasons...

  1. Your application may have crashed [check the event viewer and see if you can find event logs in your Application/System log]

  2. Your application may be crashing very frequently. If an app pool crashes for 5 times in 5 minutes [check your application pool settings for rapid fail], your application pool is disabled by IIS and you will end up getting this message.

In either case, the issue is that your worker process is failing and you should troubleshoot it from crash perspective.

What is a Crash (technically)... in ASP.NET and what to do if it happens?

Polynomial time and exponential time

Polynomial time.

A polynomial is a sum of terms that look like Constant * x^k Exponential means something like Constant * k^x

(in both cases, k is a constant and x is a variable).

The execution time of exponential algorithms grows much faster than that of polynomial ones.

Remote Procedure call failed with sql server 2008 R2

I got the samilar issue, while both SQLServer and SQLServerAgent services are running. The error is fixed by a restart of services.

Server Manager > Service > 
    SQL Server > Stop
    SQL Server > Start
    SQL Server Agent > Start

How do I convert certain columns of a data frame to become factors?

Given the following sample

myData <- data.frame(A=rep(1:2, 3), B=rep(1:3, 2), Pulse=20:25)  

then

myData$A <-as.factor(myData$A)
myData$B <-as.factor(myData$B)

or you could select your columns altogether and wrap it up nicely:

# select columns
cols <- c("A", "B")
myData[,cols] <- data.frame(apply(myData[cols], 2, as.factor))

levels(myData$A) <- c("long", "short")
levels(myData$B) <- c("1kg", "2kg", "3kg")

To obtain

> myData
      A   B Pulse
1  long 1kg    20
2 short 2kg    21
3  long 3kg    22
4 short 1kg    23
5  long 2kg    24
6 short 3kg    25

Python pandas: fill a dataframe row by row

df['y'] will set a column

since you want to set a row, use .loc

Note that .ix is equivalent here, yours failed because you tried to assign a dictionary to each element of the row y probably not what you want; converting to a Series tells pandas that you want to align the input (for example you then don't have to to specify all of the elements)

In [7]: df = pandas.DataFrame(columns=['a','b','c','d'], index=['x','y','z'])

In [8]: df.loc['y'] = pandas.Series({'a':1, 'b':5, 'c':2, 'd':3})

In [9]: df
Out[9]: 
     a    b    c    d
x  NaN  NaN  NaN  NaN
y    1    5    2    3
z  NaN  NaN  NaN  NaN

JPA mapping: "QuerySyntaxException: foobar is not mapped..."

I got the same error while using other one entity, He was annotating the class wrongly by using the table name inside the @Entity annotation without using the @Table annotation

The correct format should be

@Entity //default name similar to class name 'FooBar' OR @Entity( name = "foobar" ) for differnt entity name
@Table( name = "foobar" ) // Table name 
public class FooBar{

How do I disable a Pylint warning?

Edit "C:\Users\Your User\AppData\Roaming\Code\User\settings.json" and add 'python.linting.pylintArgs' with its lines at the end as shown below:

{
    "team.showWelcomeMessage": false,
    "python.dataScience.sendSelectionToInteractiveWindow": true,
    "git.enableSmartCommit": true,
    "powershell.codeFormatting.useCorrectCasing": true,
    "files.autoSave": "onWindowChange",
    "python.linting.pylintArgs": [
        "--load-plugins=pylint_django",
        "--errors-only"
    ],
}

Setting background colour of Android layout element

You can use android:background="#DC143C", or any other RGB values for your color. I have no problem using it this way, as stated here

Search for string within text column in MySQL

You could probably use the LIKE clause to do some simple string matching:

SELECT * FROM items WHERE items.xml LIKE '%123456%'

If you need more advanced functionality, take a look at MySQL's fulltext-search functions here: http://dev.mysql.com/doc/refman/5.1/en/fulltext-search.html

Date difference in minutes in Python

To calculate with a different time date:

from datetime import datetime

fmt = '%Y-%m-%d %H:%M:%S'
d1 = datetime.strptime('2010-01-01 16:31:22', fmt)
d2 = datetime.strptime('2010-01-03 20:15:14', fmt)

diff = d2-d1
diff_minutes = diff.seconds/60

In Java, how to append a string more efficiently?

- Each time you append or do any modification with it, it creates a new String object.

- So use append() method of StringBuilder(If thread safety is not important), else use StringBuffer(If thread safety is important.), that will be efficient way to do it.

How can I initialize base class member variables in derived class constructor?

Aggregate classes, like A in your example(*), must have their members public, and have no user-defined constructors. They are intialized with initializer list, e.g. A a {0,0}; or in your case B() : A({0,0}){}. The members of base aggregate class cannot be individually initialized in the constructor of the derived class.

(*) To be precise, as it was correctly mentioned, original class A is not an aggregate due to private non-static members

Formatting ISODate from Mongodb

JavaScript's Date object supports the ISO date format, so as long as you have access to the date string, you can do something like this:

> foo = new Date("2012-07-14T01:00:00+01:00")
Sat, 14 Jul 2012 00:00:00 GMT
> foo.toTimeString()
'17:00:00 GMT-0700 (MST)'

If you want the time string without the seconds and the time zone then you can call the getHours() and getMinutes() methods on the Date object and format the time yourself.

How can I find out the total physical memory (RAM) of my linux box suitable to be parsed by a shell script?

In Linux Kernel, present pages are physical pages of RAM which kernel can see. Literally, present pages is total size of RAM in 4KB unit.

grep present /proc/zoneinfo | awk '{sum+=$2}END{print sum*4,"KB"}'

The 'MemTotal' form /proc/meminfo is the total size of memory managed by buddy system.And we can also compute it like this:

grep managed /proc/zoneinfo | awk '{sum+=$2}END{print sum*4,"KB"}'

How to discard all changes made to a branch?

git diff master > branch.diff
git apply --reverse branch.diff

How to align an input tag to the center without specifying the width?

write this:

#siteInfo{text-align:center}
p, input{display:inline-block}

http://jsfiddle.net/XfSz6/

Encrypt and decrypt a password in Java

Here is the algorithm I use to crypt with MD5.It returns your crypted output.

   public class CryptWithMD5 {
   private static MessageDigest md;

   public static String cryptWithMD5(String pass){
    try {
        md = MessageDigest.getInstance("MD5");
        byte[] passBytes = pass.getBytes();
        md.reset();
        byte[] digested = md.digest(passBytes);
        StringBuffer sb = new StringBuffer();
        for(int i=0;i<digested.length;i++){
            sb.append(Integer.toHexString(0xff & digested[i]));
        }
        return sb.toString();
    } catch (NoSuchAlgorithmException ex) {
        Logger.getLogger(CryptWithMD5.class.getName()).log(Level.SEVERE, null, ex);
    }
        return null;


   }
}

You cannot decrypt MD5, but you can compare outputs since if you put the same string in this method it will have the same crypted output.If you want to decrypt you need to use the SHA.You will never use decription for a users password.For that always use MD5.That exception is pretty redundant.It will never throw it.

How to compare arrays in C#?

There is no static Equals method in the Array class, so what you are using is actually Object.Equals, which determines if the two object references point to the same object.

If you want to check if the arrays contains the same items in the same order, you can use the SequenceEquals extension method:

childe1.SequenceEqual(grandFatherNode)

Edit:

To use SequenceEquals with multidimensional arrays, you can use an extension to enumerate them. Here is an extension to enumerate a two dimensional array:

public static IEnumerable<T> Flatten<T>(this T[,] items) {
  for (int i = 0; i < items.GetLength(0); i++)
    for (int j = 0; j < items.GetLength(1); j++)
      yield return items[i, j];
}

Usage:

childe1.Flatten().SequenceEqual(grandFatherNode.Flatten())

If your array has more dimensions than two, you would need an extension that supports that number of dimensions. If the number of dimensions varies, you would need a bit more complex code to loop a variable number of dimensions.

You would of course first make sure that the number of dimensions and the size of the dimensions of the arrays match, before comparing the contents of the arrays.

Edit 2:

Turns out that you can use the OfType<T> method to flatten an array, as RobertS pointed out. Naturally that only works if all the items can actually be cast to the same type, but that is usually the case if you can compare them anyway. Example:

childe1.OfType<Person>().SequenceEqual(grandFatherNode.OfType<Person>())

How to compile and run a C/C++ program on the Android system

You can compile your C programs with an ARM cross-compiler:

arm-linux-gnueabi-gcc -static -march=armv7-a test.c -o test

Then you can push your compiled binary file to somewhere (don't push it in to the SD card):

adb push test /data/local/tmp/test

Traverse a list in reverse order in Python

The other answers are good, but if you want to do as List comprehension style

collection = ['a','b','c']
[item for item in reversed( collection ) ]

Difference between Hive internal tables and external tables?

An internal table data is stored in the warehouse folder, whereas an external table data is stored at the location you mentioned in table creation.

So when you delete an internal table, it deletes the schema as well as the data under the warehouse folder, but for an external table it's only the schema that you will loose.

So when you want an external table back you again after deleting it, can create a table with the same schema again and point it to the original data location. Hope it is clear now.

How to compare two files in Notepad++ v6.6.8

There is the "Compare" plugin. You can install it via Plugins > Plugin Manager.

Alternatively you can install a specialized file compare software like WinMerge.

Android Fragment onClick button Method

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.writeqrcode_main, container, false);
    // Inflate the layout for this fragment

    txt_name = (TextView) view.findViewById(R.id.name);
    txt_usranme = (TextView) view.findViewById(R.id.surname);
    txt_number = (TextView) view.findViewById(R.id.number);
    txt_province = (TextView) view.findViewById(R.id.province);
    txt_write = (EditText) view.findViewById(R.id.editText_write);
    txt_show1 = (Button) view.findViewById(R.id.buttonShow1);

    txt_show1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Log.e("Onclick","Onclick");

            txt_show1.setVisibility(View.INVISIBLE);
            txt_name.setVisibility(View.VISIBLE);
            txt_usranme.setVisibility(View.VISIBLE);
            txt_number.setVisibility(View.VISIBLE);
            txt_province.setVisibility(View.VISIBLE);
        }
    });
    return view;
}

You OK !!!!

Add two textbox values and display the sum in a third textbox automatically

Try this: Open given fiddle in CHROME

function sum() {
      var txtFirstNumberValue = document.getElementById('txt1').value;
      var txtSecondNumberValue = document.getElementById('txt2').value;
      var result = parseInt(txtFirstNumberValue) + parseInt(txtSecondNumberValue);
      if (!isNaN(result)) {
         document.getElementById('txt3').value = result;
      }
}

HTML

<input type="text" id="txt1"  onkeyup="sum();" />
<input type="text" id="txt2"  onkeyup="sum();" />
<input type="text" id="txt3" />

DEMO HERE

Your content must have a ListView whose id attribute is 'android.R.id.list'

<ListView android:id="@id/android:list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:drawSelectorOnTop="false"
        android:scrollbars="vertical"/>

How to make Python script run as service?

for my script of python, I use...

To START python script :

start-stop-daemon --start --background --pidfile $PIDFILE --make-pidfile --exec $DAEMON

To STOP python script :

PID=$(cat $PIDFILE)
kill -9 $PID
rm -f $PIDFILE

P.S.: sorry for poor English, I'm from CHILE :D

Restart container within pod

Is it possible to restart a single container

Not through kubectl, although depending on the setup of your cluster you can "cheat" and docker kill the-sha-goes-here, which will cause kubelet to restart the "failed" container (assuming, of course, the restart policy for the Pod says that is what it should do)

how do I restart the pod

That depends on how the Pod was created, but based on the Pod name you provided, it appears to be under the oversight of a ReplicaSet, so you can just kubectl delete pod test-1495806908-xn5jn and kubernetes will create a new one in its place (the new Pod will have a different name, so do not expect kubectl get pods to return test-1495806908-xn5jn ever again)

Select 2 columns in one and combine them

Yes, you can combine columns easily enough such as concatenating character data:

select col1 | col 2 as bothcols from tbl ...

or adding (for example) numeric data:

select col1 + col2 as bothcols from tbl ...

In both those cases, you end up with a single column bothcols, which contains the combined data. You may have to coerce the data type if the columns are not compatible.

SQL where datetime column equals today's date?

Looks like you're using SQL Server, in which case GETDATE() or current_timestamp may help you. But you will have to ensure that the format of the date with which you are comparing the system dates matches (timezone, granularity etc.)

e.g.

where convert(varchar(10), submission_date, 102) 
    = convert(varchar(10), getdate(), 102)

How to enable local network users to access my WAMP sites?

I have some experiences in Wamp 3.0 and Apache 2.4 .

After all works do this steps:

1- Disable nod32.

2- Add this line to <VirtualHost *:80> block in httpd-vhosts.conf file:

Require ip 192.168.100 #client ip, allow 192.168.100.### ip's access

How do I import a namespace in Razor View Page?

Finally found the answer.

@using MyNamespace

For VB.Net:

@Imports Mynamespace

Take a look at @ravy amiry's answer if you want to include a namespace across the app.

Datanode process not running in Hadoop

Error in datanode.log file

$ more /usr/local/hadoop/logs/hadoop-hduser-datanode-ubuntu.log

Shows:

java.io.IOException: Incompatible clusterIDs in /usr/local/hadoop_tmp/hdfs/datanode: namenode clusterID = CID-e4c3fed0-c2ce-4d8b-8bf3-c6388689eb82; datanode clusterID = CID-2fcfefc7-c931-4cda-8f89-1a67346a9b7c

Solution: Stop your cluster and issue the below command & then start your cluster again.

sudo rm -rf  /usr/local/hadoop_tmp/hdfs/datanode/*

Check cell for a specific letter or set of letters

Just use = IF(A1="Bla*","YES","NO"). When you insert the asterisk, it acts as a wild card for any amount of characters after the specified text.

How to close form

Your closing your instance of the settings window right after you create it. You need to display the settings window first then wait for a dialog result. If it comes back as canceled then close the window. For Example:

private void button1_Click(object sender, EventArgs e)
{
    Settings newSettingsWindow = new Settings();

    if (newSettingsWindow.ShowDialog() == DialogResult.Cancel)
    {
        newSettingsWindow.Close();
    }
}

how to hide <li> bullets in navigation menu and footer links BUT show them for listing items

The example bellow explains how to remove bullets using a css style class. You can use , similar to css class, by identifier (#id), by parent tag, etc. The same way you can use to define a css to remove bullets from the page footer.

I've used this site as a starting point.

<html>
<head>
<style type="text/css">
div.ui-menu li {
    list-style:none;
    background-image:none;
    background-repeat:none;
    background-position:0; 
}
ul
{
    list-style-type:none;
    padding:0px;
    margin:0px;
}
li
{
    background-image:url(sqpurple.gif);
    background-repeat:no-repeat;
    background-position:0px 5px; 
    padding-left:14px;
}
</style>
</head>

<body>

<div class="ui-menu">
<ul>
<li>Coffee</li>
<li>Tea</li>
<li>Coca Cola</li>
</ul>
</div>

<ul>
<li>Coffee</li>
<li>Tea</li>
<li>Coca Cola</li>
</ul>
</body>

</html>

Android - save/restore fragment state

As stated here: Why use Fragment#setRetainInstance(boolean)?

you can also use fragments method setRetainInstance(true) like this:

public class MyFragment extends Fragment {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // keep the fragment and all its data across screen rotation
        setRetainInstance(true);

    }
}

Set default host and port for ng serve in config file

If you want to specifically have your local ip address open when running ng serve you can do the following:

npm install internal-ip-cli --save
ng serve --open --host $(./node_modules/.bin/internal-ip --ipv4)

Show percent % instead of counts in charts of categorical variables

As of March 2017, with ggplot2 2.2.1 I think the best solution is explained in Hadley Wickham's R for data science book:

ggplot(mydataf) + stat_count(mapping = aes(x=foo, y=..prop.., group=1))

stat_count computes two variables: count is used by default, but you can choose to use prop which shows proportions.

Cannot resolve symbol HttpGet,HttpClient,HttpResponce in Android Studio

Please remove all jar files of Http from 'libs' folder and add below dependencies in gradle file:

compile 'org.apache.httpcomponents:httpclient:4.5'
compile 'org.apache.httpcomponents:httpcore:4.4.3'

or

useLibrary 'org.apache.http.legacy'

PHP preg_match - only allow alphanumeric strings and - _ characters

Code:

if(preg_match('/[^a-z_\-0-9]/i', $string))
{
  echo "not valid string";
}

Explanation:

  • [] => character class definition
  • ^ => negate the class
  • a-z => chars from 'a' to 'z'
  • _ => underscore
  • - => hyphen '-' (You need to escape it)
  • 0-9 => numbers (from zero to nine)

The 'i' modifier at the end of the regex is for 'case-insensitive' if you don't put that you will need to add the upper case characters in the code before by doing A-Z

What is the difference between fastcgi and fpm?

What Anthony says is absolutely correct, but I'd like to add that your experience will likely show a lot better performance and efficiency (due not to fpm-vs-fcgi but more to the implementation of your httpd).

For example, I had a quad-core machine running lighttpd + fcgi humming along nicely. I upgraded to a 16-core machine to cope with growth, and two things exploded: RAM usage, and segfaults. I found myself restarting lighttpd every 30 minutes to keep the website up.

I switched to php-fpm and nginx, and RAM usage dropped from >20GB to 2GB. Segfaults disappeared as well. After doing some research, I learned that lighttpd and fcgi don't get along well on multi-core machines under load, and also have memory leak issues in certain instances.

Is this due to php-fpm being better than fcgi? Not entirely, but how you hook into php-fpm seems to be a whole heckuva lot more efficient than how you serve via fcgi.

Google Maps shows "For development purposes only"

For me, Error has been fixed when activated Billing in google console. (I got 1-year developer trial)

MySQL direct INSERT INTO with WHERE clause

Example of how to perform a INSERT INTO SELECT with a WHERE clause.

INSERT INTO #test2 (id) SELECT id FROM #test1 WHERE id > 2

Comparing a variable with a string python not working when redirecting from bash script

When you read() the file, you may get a newline character '\n' in your string. Try either

if UserInput.strip() == 'List contents': 

or

if 'List contents' in UserInput: 

Also note that your second file open could also use with:

with open('/Users/.../USER_INPUT.txt', 'w+') as UserInputFile:     if UserInput.strip() == 'List contents': # or if s in f:         UserInputFile.write("ls")     else:         print "Didn't work" 

Declaring variables inside or outside of a loop

Please skip to the updated answer...

For those who care about performance take out the System.out and limit the loop to 1 byte. Using double (test 1/2) and using String (3/4) the elapsed times in milliseconds is given below with Windows 7 Professional 64 bit and JDK-1.7.0_21. Bytecodes (also given below for test1 and test2) are not the same. I was too lazy to test with mutable & relatively complex objects.

double

Test1 took: 2710 msecs

Test2 took: 2790 msecs

String (just replace double with string in the tests)

Test3 took: 1200 msecs

Test4 took: 3000 msecs

Compiling and getting bytecode

javac.exe LocalTest1.java

javap.exe -c LocalTest1 > LocalTest1.bc


public class LocalTest1 {

    public static void main(String[] args) throws Exception {
        long start = System.currentTimeMillis();
        double test;
        for (double i = 0; i < 1000000000; i++) {
            test = i;
        }
        long finish = System.currentTimeMillis();
        System.out.println("Test1 Took: " + (finish - start) + " msecs");
    }

}

public class LocalTest2 {

    public static void main(String[] args) throws Exception {
        long start = System.currentTimeMillis();
        for (double i = 0; i < 1000000000; i++) {
            double test = i;
        }
        long finish = System.currentTimeMillis();
        System.out.println("Test1 Took: " + (finish - start) + " msecs");
    }
}


Compiled from "LocalTest1.java"
public class LocalTest1 {
  public LocalTest1();
    Code:
       0: aload_0
       1: invokespecial #1                  // Method java/lang/Object."<init>":()V
       4: return

  public static void main(java.lang.String[]) throws java.lang.Exception;
    Code:
       0: invokestatic  #2                  // Method java/lang/System.currentTimeMillis:()J
       3: lstore_1
       4: dconst_0
       5: dstore        5
       7: dload         5
       9: ldc2_w        #3                  // double 1.0E9d
      12: dcmpg
      13: ifge          28
      16: dload         5
      18: dstore_3
      19: dload         5
      21: dconst_1
      22: dadd
      23: dstore        5
      25: goto          7
      28: invokestatic  #2                  // Method java/lang/System.currentTimeMillis:()J
      31: lstore        5
      33: getstatic     #5                  // Field java/lang/System.out:Ljava/io/PrintStream;
      36: new           #6                  // class java/lang/StringBuilder
      39: dup
      40: invokespecial #7                  // Method java/lang/StringBuilder."<init>":()V
      43: ldc           #8                  // String Test1 Took:
      45: invokevirtual #9                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      48: lload         5
      50: lload_1
      51: lsub
      52: invokevirtual #10                 // Method java/lang/StringBuilder.append:(J)Ljava/lang/StringBuilder;
      55: ldc           #11                 // String  msecs
      57: invokevirtual #9                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      60: invokevirtual #12                 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
      63: invokevirtual #13                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
      66: return
}


Compiled from "LocalTest2.java"
public class LocalTest2 {
  public LocalTest2();
    Code:
       0: aload_0
       1: invokespecial #1                  // Method java/lang/Object."<init>":()V
       4: return

  public static void main(java.lang.String[]) throws java.lang.Exception;
    Code:
       0: invokestatic  #2                  // Method java/lang/System.currentTimeMillis:()J
       3: lstore_1
       4: dconst_0
       5: dstore_3
       6: dload_3
       7: ldc2_w        #3                  // double 1.0E9d
      10: dcmpg
      11: ifge          24
      14: dload_3
      15: dstore        5
      17: dload_3
      18: dconst_1
      19: dadd
      20: dstore_3
      21: goto          6
      24: invokestatic  #2                  // Method java/lang/System.currentTimeMillis:()J
      27: lstore_3
      28: getstatic     #5                  // Field java/lang/System.out:Ljava/io/PrintStream;
      31: new           #6                  // class java/lang/StringBuilder
      34: dup
      35: invokespecial #7                  // Method java/lang/StringBuilder."<init>":()V
      38: ldc           #8                  // String Test1 Took:
      40: invokevirtual #9                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      43: lload_3
      44: lload_1
      45: lsub
      46: invokevirtual #10                 // Method java/lang/StringBuilder.append:(J)Ljava/lang/StringBuilder;
      49: ldc           #11                 // String  msecs
      51: invokevirtual #9                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      54: invokevirtual #12                 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
      57: invokevirtual #13                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
      60: return
}

UPDATED ANSWER

It's really not easy to compare performance with all the JVM optimizations. However, it is somewhat possible. Better test and detailed results in Google Caliper

  1. Some details on blog:Should you declare a variable inside a loop or before the loop?
  2. GitHub repository: https://github.com/gunduru/jvdt
  3. Test Results for double case and 100M loop (and yes all JVM details): https://microbenchmarks.appspot.com/runs/b1cef8d1-0e2c-4120-be61-a99faff625b4

DeclaredBefore 1,759.209 DeclaredInside 2,242.308

  • DeclaredBefore 1,759.209 ns
  • DeclaredInside 2,242.308 ns

Partial Test Code for double Declaration

This is not identical to the code above. If you just code a dummy loop JVM skips it, so at least you need to assign and return something. This is also recommended in Caliper documentation.

@Param int size; // Set automatically by framework, provided in the Main
/**
* Variable is declared inside the loop.
*
* @param reps
* @return
*/
public double timeDeclaredInside(int reps) {
    /* Dummy variable needed to workaround smart JVM */
    double dummy = 0;

    /* Test loop */
    for (double i = 0; i <= size; i++) {

        /* Declaration and assignment */
        double test = i;

        /* Dummy assignment to fake JVM */
        if(i == size) {
            dummy = test;
        }
    }
    return dummy;
}

/**
* Variable is declared before the loop.
*
* @param reps
* @return
*/
public double timeDeclaredBefore(int reps) {

    /* Dummy variable needed to workaround smart JVM */
    double dummy = 0;

    /* Actual test variable */
    double test = 0;

    /* Test loop */
    for (double i = 0; i <= size; i++) {

        /* Assignment */
        test = i;

        /* Not actually needed here, but we need consistent performance results */
        if(i == size) {
            dummy = test;
        }
    }
    return dummy;
}

Summary: declaredBefore indicates better performance -really tiny- and it's against the smallest scope principle. JVM should actually do this for you

Difference between "include" and "require" in php

You find the differences explained in the detailed PHP manual on the page of require:

require is identical to include except upon failure it will also produce a fatal E_COMPILE_ERROR level error. In other words, it will halt the script whereas include only emits a warning (E_WARNING) which allows the script to continue.

See @efritz's answer for an example

String Concatenation in EL

Mc Dowell's answer is right. I just want to add an improvement if in case you may need to return the variable's value as:

${ empty variable ? '<variable is empty>' : variable }

Python MYSQL update statement

It should be:

cursor.execute ("""
   UPDATE tblTableName
   SET Year=%s, Month=%s, Day=%s, Hour=%s, Minute=%s
   WHERE Server=%s
""", (Year, Month, Day, Hour, Minute, ServerID))

You can also do it with basic string manipulation,

cursor.execute ("UPDATE tblTableName SET Year=%s, Month=%s, Day=%s, Hour=%s, Minute=%s WHERE Server='%s' " % (Year, Month, Day, Hour, Minute, ServerID))

but this way is discouraged because it leaves you open for SQL Injection. As it's so easy (and similar) to do it the right waytm. Do it correctly.

The only thing you should be careful, is that some database backends don't follow the same convention for string replacement (SQLite comes to mind).

Regex matching in a Bash if statement

I'd prefer to use [:punct:] for that. Also, a-zA-Z09-9 could be just [:alnum:]:

[[ $TEST =~ ^[[:alnum:][:blank:][:punct:]]+$ ]]

How to remove commits from a pull request

You have several techniques to do it.

This post - read the part about the revert will explain in details what we want to do and how to do it.

Here is the most simple solution to your problem:

# Checkout the desired branch
git checkout <branch>

# Undo the desired commit
git revert <commit>

# Update the remote with the undo of the code
git push origin <branch>

The revert command will create a new commit with the undo of the original commit.

What is the easiest way to initialize a std::vector with hardcoded elements?

I build my own solution using va_arg. This solution is C++98 compliant.

#include <cstdarg>
#include <iostream>
#include <vector>

template <typename T>
std::vector<T> initVector (int len, ...)
{
  std::vector<T> v;
  va_list vl;
  va_start(vl, len);
  for (int i = 0; i < len; ++i)
    v.push_back(va_arg(vl, T));
  va_end(vl);
  return v;
}

int main ()
{
  std::vector<int> v = initVector<int> (7,702,422,631,834,892,104,772);
  for (std::vector<int>::const_iterator it = v.begin() ; it != v.end(); ++it)
    std::cout << *it << std::endl;
  return 0;
}

Demo

How to prevent "The play() request was interrupted by a call to pause()" error?

try it

n.pause();
n.currentTime = 0;
var nopromise = {
   catch : new Function()
};
(n.play() || nopromise).catch(function(){}); ;

How do I get to IIS Manager?

First of all, you need to check that the IIS is installed in your machine, for that you can go to:

Control Panel --> Add or Remove Programs --> Windows Features --> And Check if Internet Information Services is installed with at least the 'Web Administration Tools' Enabled and The 'World Wide Web Service'

If not, check it, and Press Accept to install it.

Once that is done, you need to go to Administrative Tools in Control Panel and the IIS Will be there. Or simply run inetmgr (after Win+R).

Edit: You should have something like this: enter image description here

Escape double quotes in Java

Use Java's replaceAll(String regex, String replacement)

For example, Use a substitution char for the quotes and then replace that char with \"

String newstring = String.replaceAll("%","\"");

or replace all instances of \" with \\\"

String newstring = String.replaceAll("\"","\\\"");

nginx: how to create an alias url route?

server {
  server_name example.com;
  root /path/to/root;
  location / {
    # bla bla
  }
  location /demo {
    alias /path/to/root/production/folder/here;
  }
}

If you need to use try_files inside /demo you'll need to replace alias with a root and do a rewrite because of the bug explained here

Iterating over each line of ls -l output

It depends what you want to do with each line. awk is a useful utility for this type of processing. Example:

 ls -l | awk '{print $9, $5}'

.. on my system prints the name and size of each item in the directory.

Adding n hours to a date in Java?

You can do it with Joda DateTime API

DateTime date= new DateTime(dateObj);
date = date.plusHours(1);
dateObj = date.toDate();

Is it possible to create a temporary table in a View and drop it after select?

No, a view consists of a single SELECT statement. You cannot create or drop tables in a view.

Maybe a common table expression (CTE) can solve your problem. CTEs are temporary result sets that are defined within the execution scope of a single statement and they can be used in views.

Example (taken from here) - you can think of the SalesBySalesPerson CTE as a temporary table:

CREATE VIEW vSalesStaffQuickStats
AS
  WITH SalesBySalesPerson (SalesPersonID, NumberOfOrders, MostRecentOrderDate)
      AS
      (
            SELECT SalesPersonID, COUNT(*), MAX(OrderDate)
            FROM Sales.SalesOrderHeader
            GROUP BY SalesPersonID
      )
  SELECT E.EmployeeID,
         EmployeeOrders = OS.NumberOfOrders,
         EmployeeLastOrderDate = OS.MostRecentOrderDate,
         E.ManagerID,
         ManagerOrders = OM.NumberOfOrders,
         ManagerLastOrderDate = OM.MostRecentOrderDate
  FROM HumanResources.Employee AS E
  INNER JOIN SalesBySalesPerson AS OS ON E.EmployeeID = OS.SalesPersonID
  LEFT JOIN SalesBySalesPerson AS OM ON E.ManagerID = OM.SalesPersonID
GO

Performance considerations

Which are more performant, CTE or temporary tables?

Allow only numeric value in textbox using Javascript

use following code

function numericFilter(txb) {
   txb.value = txb.value.replace(/[^\0-9]/ig, "");
}

call it in on key up

<input type="text" onKeyUp="numericFilter(this);" />

cut or awk command to print first field of first row

sed -n 1p /etc/*release |cut -d " " -f1

if tab delimited:

sed -n 1p /etc/*release |cut -f1

XAMPP MySQL password setting (Can not enter in PHPMYADMIN)

First Issue: You want to run Mysql server from Mysql and from Xampp also want to browse phpmyadmin so that you can operate database.Then follow the rules:

From "Xampp/phpmyadmin" directory in config.inc.php file find the below code. And follow the given instructions below. I have tried like this and I was successful to run both localhost/phpMyAdmin on browser, MySQL Command prompt as well as MySQL query browser.

$cfg['Servers'][$i]['auth_type']    = 'config';
$cfg['Servers'][$i]['user']         = 'pma';
$cfg['Servers'][$i]['password']     = '';
$cfg['Servers'][$i]['controluser']  = 'user_name/root';   
$cfg['Servers'][$i]['controlpass']  = 'passwaord';

And replace the above each statement with the below each corresponding code.

$cfg['Servers'][$i]['auth_type']    = 'config';
$cfg['Servers'][$i]['user']         = 'root';
$cfg['Servers'][$i]['password']     = 'Muhammad Ashikuzzaman';
$cfg['Servers'][$i]['controluser']  = 'root';   
$cfg['Servers'][$i]['controlpass']  = 'Muhammad Ashikuzzaman';

Second Issue: Way 1 : You can quit Skype first. And when Apche server is started then again you can run Skype. If you want to run Apache in another port then replace in xampp/apache/conf/httpd.conf "ServerName localhost:80" by "ServerName localhost:81" At line 184. After that even it may not work. Then replace

#Listen 0.0.0.0:80
#Listen [::]:80
Listen 80 

by

#Listen 0.0.0.0:81
#Listen [::]:81
Listen 81

at line 45

Way 2 : If you want to use port 80. Then follow this. In Windows 8 “World Wide Publishing Service is using this port and stopping this service will free the port 80 and you can connect Apache using this port. To stop the service go to the “Task manager –> Services tab”, right click the “World Wide Publishing Service” and stop. If you don't find there then go to "Run > services.msc" and again find there and right click the “World Wide Publishing Service” and stop.

If you didn't find “World Wide Publishing Service” there then go to "Run>>resmon.exe>> Network Tab>>Listening Ports" and see which process is using port 80.

And from "Overview>>CPU" just Right click on that process and click "End Process Tree". If that process is system that might be a critical issue.

Parse JSON with R

The function fromJSON() in RJSONIO, rjson and jsonlite don't return a simple 2D data.frame for complex nested json objects.

To overcome this you can use tidyjson. It takes in a json and always returns a data.frame. It is currently not availble in CRAN, you can get it here: https://github.com/sailthru/tidyjson

Update: tidyjson is now available in cran, you can install it directly using install.packages("tidyjson")

What is the difference between ArrayList.clear() and ArrayList.removeAll()?

They serve different purposes. clear() clears an instance of the class, removeAll() removes all the given objects and returns the state of the operation.

Can a unit test project load the target application's app.config file?

I couldn't get any of these suggestions to work with nUnit 2.5.10 so I ended up using nUnit's Project -> Edit functionality to specify the config file to target (as others have said it needs to be in the same folder as the .nunit file itself). The positive side of this is that I can give the config file a Test.config name which makes it much clearer what it is and why it is)

Html.DropdownListFor selected value not being set

When you pass an object like this:

new SelectList(Model, "Code", "Name", 0)

you are saying: the Source (Model) and Key ("Code") the Text ("Name") and the selected value 0. You probably do not have a 0 value in your source for Code property, so the HTML Helper will select the first element to pass the real selectedValue to this control.

What is Android's file system?

Android supports all filesystems supported by the Linux kernel, except for a few ported ones like NTFS.

The SD card is formatted as ext3, for example.

How do I extract part of a string in t-sql

declare @data as varchar(50)
set @data='ciao335'


--get text
Select Left(@Data, PatIndex('%[0-9]%', @Data + '1') - 1)    ---->>ciao

--get numeric
Select right(@Data, len(@data) - (PatIndex('%[0-9]%', @Data )-1) )   ---->>335

How do I force make/GCC to show me the commands?

To invoke a dry run:

make -n

This will show what make is attempting to do.

maven error: package org.junit does not exist

In my case, the culprit was not distinguish the main and test sources folder within pom.xml (generated by eclipse maven project)

<build>
    <sourceDirectory>src</sourceDirectory>
    ....
</build>

If you override default source folder settings in pom file, you must explicitly set the main AND test source folders!!!!

<build>
    <sourceDirectory>src/main/java</sourceDirectory>
    <testSourceDirectory>src/test/java</testSourceDirectory>
    ....
</build>

Timestamp Difference In Hours for PostgreSQL

Get fields where a timestamp is greater than date in postgresql:

SELECT * from yourtable 
WHERE your_timestamp_field > to_date('05 Dec 2000', 'DD Mon YYYY');

Subtract minutes from timestamp in postgresql:

SELECT * from yourtable 
WHERE your_timestamp_field > current_timestamp - interval '5 minutes'

Subtract hours from timestamp in postgresql:

SELECT * from yourtable 
WHERE your_timestamp_field > current_timestamp - interval '5 hours'

Transpose/Unzip Function (inverse of zip)?

Consider using more_itertools.unzip:

>>> from more_itertools import unzip
>>> original = [('a', 1), ('b', 2), ('c', 3), ('d', 4)]
>>> [list(x) for x in unzip(original)]
[['a', 'b', 'c', 'd'], [1, 2, 3, 4]]     

How do I set the figure title and axes labels font size in Matplotlib?

7 (best solution)

 from numpy import*
 import matplotlib.pyplot as plt
 X = linspace(-pi, pi, 1000)

class Crtaj:

    def nacrtaj(self,x,y):
         self.x=x
         self.y=y
         return plt.plot (x,y,"om")

def oznaci(self):
    return plt.xlabel("x-os"), plt.ylabel("y-os"), plt.grid(b=True)

6 (slightly worse solution)

from numpy import*
M = array([[3,2,3],[1,2,6]])
class AriSred(object):
    def __init__(self,m):
    self.m=m
    
def srednja(self):
    redovi = len(M)
    stupci = len (M[0])
    lista=[]
    a=0
    suma=0
    while a<stupci:
        for i in range (0,redovi):
            suma=suma+ M[i,a]
        lista.append(suma)
        a=a+1
        suma=0
    b=array(lista) 
    b=b/redovi
    return b



OBJ = AriSred(M)
sr = OBJ.srednja()

Grep for beginning and end of line?

are you parsing output of ls -l?

If you are, and you just want to get the file name

find . -iname "*[0-9]" 

If you have no choice because usrLog.txt is created by something/someone else and you absolutely must use this file, other options include

awk '/^[-d].*[0-9]$/' file

Ruby(1.9+)

ruby -ne 'print if /^[-d].*[0-9]$/' file

Bash

while read -r line ; do  case $line in [-d]*[0-9] ) echo $line;  esac; done < file

What are ABAP and SAP?

SAP is a company and offers a full Enterprise Resource Planning (ERP) system, business platform, and the associated modules (financials, general ledger, &c).

ABAP is the primary programming language used to write SAP software and customizations. It would do it injustice to think of it as COBOL and SQL on steroids, but that gives you an idea. ABAP runs within the SAP system.

SAP and ABAP abstract the DB and run atop various underlying DBMSs.

SAP produces other things as well and even publicly says they dabble in Java and even produce a J2EE container, but tried-and-true SAP is ABAP through-and-through.

Error: No Firebase App '[DEFAULT]' has been created - call Firebase App.initializeApp()

The answer may already be given somewhere but here is my take to this error which may be thrown for multiple reasons:

  1. Default app is initialized after the other one. Correct way is to initialize the default app first and then the rest.
  2. firebase.apps.app() is being called before default app initialization. This code is basically returning the default app instance. Since it is not present, hence the error.
  3. Lastly, you are initializing other firebase services like auth, database, firestore, etc before app is initialized.

Git Push Error: insufficient permission for adding an object to repository database

I'll add my two cents just as a way to discover files with a specific ownership inside a directory.

The issue was caused by running some git command as root. The received message was:

$ git commit -a -m "fix xxx"
error: insufficient permission for adding an object to repository database .git/objects
error: setup.sh: failed to insert into database

I first looked at git config -l, then I resolved with:

find .git/ -exec stat --format="%G %n" {} + |grep root

chown -R $(id -un):$(id -gn) .git/objects/

git commit -a -m "fixed git objects ownership"

How can I make a list of lists in R?

As other answers pointed out in a more complicated way already, you did already create a list of lists! It's just the odd output of R that confuses (everybody?). Try this:

> str(list_all)
List of 2
 $ :List of 2
  ..$ : num 1
  ..$ : num 2
 $ :List of 2
  ..$ : chr "a"
  ..$ : chr "b"

And the most simple construction would be this:

> str(list(list(1, 2), list("a", "b")))
List of 2
 $ :List of 2
  ..$ : num 1
  ..$ : num 2
 $ :List of 2
  ..$ : chr "a"
  ..$ : chr "b"

How do I use .toLocaleTimeString() without displaying seconds?

Here's a function that will do it, with comments that explain:

  function displayNiceTime(date){
    // getHours returns the hours in local time zone from 0 to 23
    var hours = date.getHours()
    // getMinutes returns the minutes in local time zone from 0 to 59
    var minutes =  date.getMinutes()
    var meridiem = " AM"

    // convert to 12-hour time format
    if (hours > 12) {
      hours = hours - 12
      meridiem = ' PM'
    }
    else if (hours === 0){
      hours = 12
    }

    // minutes should always be two digits long
    if (minutes < 10) {
      minutes = "0" + minutes.toString()
    }
    return hours + ':' + minutes + meridiem
  }

Since, as others have noted, toLocaleTimeString() can be implemented differently in different browsers, this way gives better control.

To learn more about the Javascript Date object, this is a good resource: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date

Get current folder path

System.AppDomain.CurrentDomain.BaseDirectory

This will give you running directory of your application. This even works for web applications. Afterwards you can reach your file.

How to update a record using sequelize for node?

January 2020 Answer
The thing to understand is that there's an update method for the Model and a separate update method for an Instance (record). Model.update() updates ALL matching records and returns an array see Sequelize documentation. Instance.update() updates the record and returns an instance object.

So to update a single record per the question, the code would look something like this:

SequlizeModel.findOne({where: {id: 'some-id'}})
.then(record => {
  
  if (!record) {
    throw new Error('No record found')
  }

  console.log(`retrieved record ${JSON.stringify(record,null,2)}`) 

  let values = {
    registered : true,
    email: '[email protected]',
    name: 'Joe Blogs'
  }
  
  record.update(values).then( updatedRecord => {
    console.log(`updated record ${JSON.stringify(updatedRecord,null,2)}`)
    // login into your DB and confirm update
  })

})
.catch((error) => {
  // do seomthing with the error
  throw new Error(error)
})

So, use Model.findOne() or Model.findByPkId() to get a handle a single Instance (record) and then use the Instance.update()

Adding and removing style attribute from div with jquery

In case of .css method in jQuery for !important rule will not apply.

In this case we should use .attr function.

For Example: If you want to add style as below:

<div id='voltaic_holder' style='position:absolute;top:-75px !important'>

You should use:

$("#voltaic_holder").attr("style", "position:absolute;top:-75px !important");

Hope it helps some one.

Any way to generate ant build.xml file automatically from Eclipse?

I'm the one who donated the Ant export filter to Eclipse. I added the auto export feature, but only to my personal plug-in eclipse2ant, which I still maintain to coordinate bug fixes.

Unfortunately I have no time to merge it to the official Eclipse builds.

How to update a value in a json file and save it through node.js

For those looking to add an item to a json collection

function save(item, path = './collection.json'){
    if (!fs.existsSync(path)) {
        fs.writeFile(path, JSON.stringify([item]));
    } else {
        var data = fs.readFileSync(path, 'utf8');  
        var list = (data.length) ? JSON.parse(data): [];
        if (list instanceof Array) list.push(item)
        else list = [item]  
        fs.writeFileSync(path, JSON.stringify(list));
    }
}

How to run a Command Prompt command with Visual Basic code?

Or, you could do it the really simple way.

Dim OpenCMD 
OpenCMD = CreateObject("wscript.shell")
OpenCMD.run("Command Goes Here")

writing integer values to a file using out.write()

write() only takes a single string argument, so you could do this:

outf.write(str(num))

or

outf.write('{}'.format(num))  # more "modern"
outf.write('%d' % num)        # deprecated mostly

Also note that write will not append a newline to your output so if you need it you'll have to supply it yourself.

Aside:

Using string formatting would give you more control over your output, so for instance you could write (both of these are equivalent):

num = 7
outf.write('{:03d}\n'.format(num))

num = 12
outf.write('%03d\n' % num)          

to get three spaces, with leading zeros for your integer value followed by a newline:

007
012

format() will be around for a long while, so it's worth learning/knowing.

how to set radio option checked onload with jQuery

Say you had radio buttons like these, for example:

<input type='radio' name='gender' value='Male'>
<input type='radio' name='gender' value='Female'>

And you wanted to check the one with a value of "Male" onload if no radio is checked:

$(function() {
    var $radios = $('input:radio[name=gender]');
    if($radios.is(':checked') === false) {
        $radios.filter('[value=Male]').prop('checked', true);
    }
});

How to check if keras tensorflow backend is GPU or CPU version?

According to the documentation.

If you are running on the TensorFlow or CNTK backends, your code will automatically run on GPU if any available GPU is detected.

You can check what all devices are used by tensorflow by -

from tensorflow.python.client import device_lib
print(device_lib.list_local_devices())

Also as suggested in this answer

import tensorflow as tf
sess = tf.Session(config=tf.ConfigProto(log_device_placement=True))

This will print whether your tensorflow is using a CPU or a GPU backend. If you are running this command in jupyter notebook, check out the console from where you have launched the notebook.

If you are sceptic whether you have installed the tensorflow gpu version or not. You can install the gpu version via pip.

pip install tensorflow-gpu

How to extract svg as file from web page

When you're on a page that doesn't let you reach the SVG via its own URL (e.g. an inline SVG), you can print the page and select PDF as the target output. Once the PDF has been saved, you can open it in an image editor that supports vector (e.g. Adobe Illustrator), select only the vector art you want, and cut and paste it into a new file in the image editor.

Best way to center a <div> on a page vertically and horizontally?

Solution

Using only two lines of CSS, utilizing the magical power of Flexbox

.parent { display: flex; }
.child { margin: auto }

Stupid error: Failed to load resource: net::ERR_CACHE_MISS

Google declares that this is not a failure, but some "misleading error reports". This bug will be fixed in version 40 of chrome.

You can read this:

Chromium forum
Chromium forum
Patch

How to add a right button to a UINavigationController?

You can try

self.navigationBar.topItem.rightBarButtonItem = anotherButton;

angular-cli server - how to proxy API requests to another server?

I'll explain what you need to know on the example below:

{
  "/folder/sub-folder/*": {
    "target": "http://localhost:1100",
    "secure": false,
    "pathRewrite": {
      "^/folder/sub-folder/": "/new-folder/"
    },
    "changeOrigin": true,
    "logLevel": "debug"
  }
}
  1. /folder/sub-folder/*: path says: When I see this path inside my angular app (the path can be stored anywhere) I want to do something with it. The * character indicates that everything that follows the sub-folder will be included. For instance, if you have multiple fonts inside /folder/sub-folder/, the * will pick up all of them

  2. "target": "http://localhost:1100" for the path above make target URL the host/source, therefore in the background we will have http://localhost:1100/folder/sub-folder/

  3. "pathRewrite": { "^/folder/sub-folder/": "/new-folder/" }, Now let's say that you want to test your app locally, the url http://localhost:1100/folder/sub-folder/ may contain an invalid path: /folder/sub-folder/. You want to change that path to a correct one which is http://localhost:1100/new-folder/, therefore the pathRewrite will become useful. It will exclude the path in the app(left side) and include the newly written one (right side)

  4. "secure": represents wether we are using http or https. If https is used in the target attribute then set secure attribute to true otherwise set it to false

  5. "changeOrigin": option is only necessary if your host target is not the current environment, for example: localhost. If you want to change the host to www.something.com which would be the target in the proxy then set the changeOrigin attribute to "true":

  6. "logLevel": attribute specifies wether the developer wants to display proxying on his terminal/cmd, hence he would use the "debug" value as shown in the image

In general, the proxy helps in developing the application locally. You set your file paths for production purpose and if you have all these files locally inside your project you may just use proxy to access them without changing the path dynamically in your app.

If it works, you should see something like this in your cmd/terminal.

enter image description here

Adding a new line/break tag in XML

You probably need to put it in a CDATA block to preserve whitespace

<?xml version="1.0" encoding="utf-8"?> <?xml-stylesheet type="text/xsl" href="dummy.xsl"?>   
   <item>      
      <summary>
         <![CDATA[Tootsie roll tiramisu macaroon wafer carrot cake.                       
            Danish topping sugar plum tart bonbon caramels cake.]]>
      </summary>   
   </item> 

Output single character in C

Be careful of difference between 'c' and "c"

'c' is a char suitable for formatting with %c

"c" is a char* pointing to a memory block with a length of 2 (with the null terminator).

iText - add content to existing PDF file

Gutch's code is close, but it'll only work right if:

  • There are no annotations (links, fields, etc), no Document Structure/Marked Content, no bookmarks, no document-level script, etc, etc, etc...
  • The page size happens to be A.4 (decent odds, but it won't work on any ol' PDF you happen to come across)
  • You don't mind losing all the original document metadata (producer, creation date, possibly author/title/keywords), and maybe the document ID. You can't copy the creation date and doc ID unless you do some pretty deep hackery on iText itself).

The Approved Method is to do it the other way around. Open the existing document with a PdfStamper, and use the returned PdfContentByte from getOverContent() to write text (and whatever else you might need) directly to the page. No second document needed.

And you can use a ColumnText to handle layout and such for you... no need to get down and dirty with beginText(),setFontAndSize(),drawText(),drawText()...,endText().

file_get_contents(): SSL operation failed with code 1, Failed to enable crypto

At first you need to have enabled curl extension in PHP. Then you can use this function:

function file_get_contents_ssl($url) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
    curl_setopt($ch, CURLOPT_HEADER, false);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_REFERER, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 3000); // 3 sec.
    curl_setopt($ch, CURLOPT_TIMEOUT, 10000); // 10 sec.
    $result = curl_exec($ch);
    curl_close($ch);
    return $result;
}

It works similar to function file_get_contents(..).

Example:

echo file_get_contents_ssl("https://www.example.com/");

Output:

<!doctype html>
<html>
<head>
    <title>Example Domain</title>
...

DateTime's representation in milliseconds?

SELECT CAST(DATEDIFF(S, '1970-01-01', SYSDATETIME()) AS BIGINT) * 1000

This does not give you full precision, but DATEDIFF(MS... causes overflow. If seconds are good enough, this should do it.

Jquery: how to trigger click event on pressing enter key

Are you trying to mimic a click on a button when the enter key is pressed? If so you may need to use the trigger syntax.

Try changing

$('input[name = butAssignProd]').click();

to

$('input[name = butAssignProd]').trigger("click");

If this isn't the problem then try taking a second look at your key capture syntax by looking at the solutions in this post: jQuery Event Keypress: Which key was pressed?

Which Eclipse version should I use for an Android app?

I would recommend at least Eclipse Indigo (v 3.7) for Android Development because even though a minimum of Helios (v 3.6) is required for ADT 22.0.1 as explained here...

http://developer.android.com/tools/sdk/eclipse-adt.html

... Indigo is required for Android NDK development using CDT, as explained here:

http://tools.android.com/recent/usingthendkplugin

How to read data from excel file using c#

I don't have a machine available to test this but it should work. First you will probably need to install the either the 2007 Office System Driver: Data Connectivity Components or the Microsoft Access Database Engine 2010 Redistributable. Then try the following code, note you will need to change the name of the Sheet in the Select statement below to match sheetname in your excel file:

using System.Data;
using System.Data.OleDb;

namespace Data_Migration_Process_Creator
{
    class Class1
    {
        private DataTable GetDataTable(string sql, string connectionString)
        {
            DataTable dt = null;

            using (OleDbConnection conn = new OleDbConnection(connectionString))
            {
                conn.Open();
                using (OleDbCommand cmd = new OleDbCommand(sql, conn))
                {
                    using (OleDbDataReader rdr = cmd.ExecuteReader())
                    {
                        dt.Load(rdr);
                        return dt;
                    }
                }
            }
        }

        private void GetExcel()
        {
            string fullPathToExcel = "<Path to Excel file>"; //ie C:\Temp\YourExcel.xls
            string connString = string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties='Excel 12.0;HDR=yes'", fullPathToExcel);
            DataTable dt = GetDataTable("SELECT * from [SheetName$]", connString);

            foreach (DataRow dr in dt.Rows)
            {
                //Do what you need to do with your data here
            }
        }
    }
}

Note: I don't have an environment to test this in (One with Office installed) so I can't say if it will work in your environment or not but I don't see why it shouldn't work.

AngularJS error: 'argument 'FirstCtrl' is not a function, got undefined'

You have 2 unnamed ng-app directives in your html.
Lose the one in your div.

Update
Let's try a different approach.
Define a module in your js file and assign the ng-appdirective to it. After that, define the controller like an ng component, not as a simple function:

<div ng-app="myAppName">  
<!-- or what's the root node of your angular app -->

and the js part:

angular.module('myAppName', [])
    .controller('FirstCtrl', function($scope) {
         $scope.data = {message: 'Hello'};
    });

Here's an online demo that is doing just that : http://jsfiddle.net/FssbL/1/

LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup

I had this error when accidentally putting the wmain inside a namespace. wmain should not be in any namespace. Moreover, I had a main function in one of the libs I was using, and VS took the main from there, what made it even stranger.

Scrolling a div with jQuery

I know this is ages old, but upon searching for something similar this morning, and reading up on Atømix' response (as this is what we're aiming on achieving), I found this: http://www.switchonthecode.com/tutorials/using-jquery-slider-to-scroll-a-div.

Just putting that there in case anyone else needs a solution. :)

How do I use Ruby for shell scripting?

"How do I write ruby" is a little beyond the scope of SO.

But to turn these ruby scripts into executable scripts, put this as the first line of your ruby script:

#!/path/to/ruby

Then make the file executable:

chmod a+x myscript.rb

and away you go.

Can I change the viewport meta tag in mobile safari on the fly?

in your <head>

<meta id="viewport"
      name="viewport"
      content="width=1024, height=768, initial-scale=0, minimum-scale=0.25" />

somewhere in your javascript

document.getElementById("viewport").setAttribute("content",
      "initial-scale=0.5; maximum-scale=1.0; user-scalable=0;");

... but good luck with tweaking it for your device, fiddling for hours... and i'm still not there!

source

jQuery - If element has class do this

First, you're missing some parentheses in your conditional:

if ($("#about").hasClass("opened")) {
  $("#about").animate({right: "-700px"}, 2000);
}

But you can also simplify this to:

$('#about.opened').animate(...);

If #about doesn't have the opened class, it won't animate.

If the problem is with the animation itself, we'd need to know more about your element positioning (absolute? absolute inside relative parent? does the parent have layout?)

Using ls to list directories and their total sizes

place in init script like .bashrc ... adjust def as needed.

duh() {
  # shows disk utilization for a path and depth level
  path="${1:-$PWD}"
  level="${2:-0}"
  du "$path" -h --max-depth="$level"
}

How do I "decompile" Java class files?

There are a few programs you can use. You will get the actual Java code, but sometimes the code will have been obfuscated so methods are named by one letter or number or a random mix of letters and numbers.

DJ Decompiler Mocha

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 32 bytes)

128M == 134217728, the number you are seeing.

The memory limit is working fine. When it says it tried to allocate 32 bytes, that the amount requested by the last operation before failing.

Are you building any huge arrays or reading large text files? If so, remember to free any memory you don't need anymore, or break the task down into smaller steps.

Dependency Injection vs Factory Pattern

I use both to create an Inversion Of Control strategy with more readability for developers who need to maintain it after me.

I use a Factory to create my different Layer objects (Business, Data Access).

ICarBusiness carBusiness = BusinessFactory.CreateCarBusiness();

Another developer will see this and when creating an Business Layer object he looks in BusinessFactory and Intellisense gives the developer all the possible Business Layers to create. Doesn't have to play the game, find the Interface I want to create.

This structure is already Inversion Of Control. I am no longer responsible for creating the specific object. But you still need to ensure Dependency Injection to be able to change things easily. Creating your own custom Dependency Injection is ridiculous, so I use Unity. Within the CreateCarBusiness() I ask Unity to Resolve which class belongs to this and it’s lifetime.

So my code Factory Dependency Injection structure is:

public static class BusinessFactory
{
    public static ICarBusiness CreateCarBusiness()
    {
       return Container.Resolve<ICarBusiness>();
    }
}

Now I have the benefit of both. My code is also more readable for other developers as towards scopes of my objects I use, instead of Constructor Dependency Injection which just says every object is available when the class is created.

I use this to change my Database Data Access to a custom coded Data Access layer when I create Unit Tests. I don’t want my Unit Tests to communicate with databases, webservers, e-mail servers etc. They need to test my Business Layer because that’s where the intelligence is.

How to toggle boolean state of react component?

Since nobody posted this, I am posting the correct answer. If your new state update depends on the previous state, always use the functional form of setState which accepts as argument a function that returns a new state.

In your case:

this.setState(prevState => ({
  check: !prevState.check
}));

See docs


Since this answer is becoming popular, adding the approach that should be used for React Hooks (v16.8+):

If you are using the useState hook, then use the following code (in case your new state depends on the previous state):

const [check, setCheck] = useState(false);
// ...
setCheck(prevCheck => !prevCheck);

No Application Encryption Key Has Been Specified

From Encryption - Laravel - The PHP Framework For Web Artisans:

"Before using Laravel's encrypter, you must set a key option in your config/app.php configuration file. You should use the php artisan key:generate command to generate this key"

I found that using this complex internet query in google.com:

"laravel add encrption key" (Yes, it worked even with the typo!)

Spring @Transactional read-only propagation

By default transaction propagation is REQUIRED, meaning that the same transaction will propagate from a transactional caller to transactional callee. In this case also the read-only status will propagate. E.g. if a read-only transaction will call a read-write transaction, the whole transaction will be read-only.

Could you use the Open Session in View pattern to allow lazy loading? That way your handle method does not need to be transactional at all.

Repeating a function every few seconds

There are lot of different Timers in the .NET BCL:

When to use which?

  • System.Timers.Timer, which fires an event and executes the code in one or more event sinks at regular intervals. The class is intended for use as a server-based or service component in a multithreaded environment; it has no user interface and is not visible at runtime.
  • System.Threading.Timer, which executes a single callback method on a thread pool thread at regular intervals. The callback method is defined when the timer is instantiated and cannot be changed. Like the System.Timers.Timer class, this class is intended for use as a server-based or service component in a multithreaded environment; it has no user interface and is not visible at runtime.
  • System.Windows.Forms.Timer (.NET Framework only), a Windows Forms component that fires an event and executes the code in one or more event sinks at regular intervals. The component has no user interface and is designed for use in a single-threaded environment; it executes on the UI thread.
  • System.Web.UI.Timer (.NET Framework only), an ASP.NET component that performs asynchronous or synchronous web page postbacks at a regular interval.
  • System.Windows.Threading.DispatcherTimer, a timer that's integrated into the Dispatcher queue. This timer is processed with a specified priority at a specified time interval.

Source


Some of them needs explicit Start call to begin ticking (for example System.Timers, System.Windows.Forms). And an explicit Stop to finish ticking.

using TimersTimer = System.Timers.Timer;

static void Main(string[] args)
{
    var timer = new TimersTimer(1000);
    timer.Elapsed += (s, e) => Console.WriteLine("Beep");
    Thread.Sleep(1000); //1 second delay
    timer.Start();
    Console.ReadLine();
    timer.Stop();

}

While on the other hand there are some Timers (like: System.Threading) where you don't need explicit Start and Stop calls. (The provided delegate will run a background thread.) Your timer will tick until you or the runtime dispose it.

So, the following two versions will work in the same way:

using ThreadingTimer = System.Threading.Timer;

static void Main(string[] args)
{
    var timer = new ThreadingTimer(_ => Console.WriteLine("Beep"), null, TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(1));
    Console.ReadLine();
}
using ThreadingTimer = System.Threading.Timer;
static void Main(string[] args)
{
    StartTimer();
    Console.ReadLine();
}

static void StartTimer()
{
    var timer = new ThreadingTimer(_ => Console.WriteLine("Beep"), null, TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(1));
}

But if your timer disposed then it will stop ticking obviously.

using ThreadingTimer = System.Threading.Timer; 

static void Main(string[] args)
{
    StartTimer();
    GC.Collect(0);
    Console.ReadLine();
}

static void StartTimer()
{
    var timer = new ThreadingTimer(_ => Console.WriteLine("Beep"), null, TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(1));
}

How to delete rows in tables that contain foreign keys to other tables

First, as a one-time data-scrubbing exercise, delete the orphaned rows e.g.

DELETE 
  FROM ReferencingTable 
 WHERE NOT EXISTS (
                   SELECT * 
                     FROM MainTable AS T1
                    WHERE T1.pk_col_1 = ReferencingTable.pk_col_1
                  );

Second, as a one-time schema-alteration exercise, add the ON DELETE CASCADE referential action to the foreign key on the referencing table e.g.

ALTER TABLE ReferencingTable DROP 
   CONSTRAINT fk__ReferencingTable__MainTable;

ALTER TABLE ReferencingTable ADD 
   CONSTRAINT fk__ReferencingTable__MainTable 
      FOREIGN KEY (pk_col_1)
      REFERENCES MainTable (pk_col_1)
      ON DELETE CASCADE;

Then, forevermore, rows in the referencing tables will automatically be deleted when their referenced row is deleted.

JFrame Maximize window

I've tried the solutions in this thread and the ones here, but simply calling setExtendedState(getExtendedState()|Frame.MAXIMIZED_BOTH); right after calling setVisible(true); apparently does not work for my environment (Windows 10, JDK 1.8, my taskbar is on the right side of my screen). Doing it this way still leaves a tiny space on the left, right and bottom .

What did work for me however, is calling setExtendedState(... when the window is activated, like so:

public class SomeFrame extends JFrame {

    public SomeFrame() {
        // ...
        setVisible(true);
        setResizable(true);
        // if you are calling setSize() for fallback size, do that here
        addWindowListener (
            new WindowAdapter() {
                private boolean shown = false;
                @Override
                public void windowActivated(WindowEvent we) {
                    if(shown) return;
                    shown = true;
                    setExtendedState(getExtendedState()|JFrame.MAXIMIZED_BOTH);
                }
            }
        );
    }
}

Detecting arrow key presses in JavaScript

Arrow Keys are triggered on keyup

$(document).on("keyup", "body", function(e) {
 if (e.keyCode == 38) {
    // up arrow
    console.log("up arrow")
  }
  if (e.keyCode == 40) {
      // down arrow
      console.log("down arrow")
  }
  if (e.keyCode == 37) {
    // left arrow
    console.log("lefy arrow")
  }
  if (e.keyCode == 39) {
    // right arrow
    console.log("right arrow")
  }
})

onkeydown allows ctrl, alt, shits

onkeyup allows tab, up arrows, down arrows, left arrows, down arrows

Selecting all text in HTML text input when clicked

The problem with catching the click event is that each subsequent click within the text will select it again, whereas the user was probably expecting to reposition the cursor.

What worked for me was declaring a variable, selectSearchTextOnClick, and setting it to true by default. The click handler checks that the variable's still true: if it is, it sets it to false and performs the select(). I then have a blur event handler which sets it back to true.

Results so far seem like the behavior I'd expect.

(Edit: I neglected to say that I'd tried catching the focus event as someone suggested,but that doesn't work: after the focus event fires, the click event can fire, immediately deselecting the text).

How to load a tsv file into a Pandas DataFrame?

Try this:

import pandas as pd
DataFrame = pd.read_csv("dataset.tsv", sep="\t")

How to remove certain characters from a string in C++?

Here's yet another alternative:

template<typename T>
void Remove( std::basic_string<T> & Str, const T * CharsToRemove )
{
    std::basic_string<T>::size_type pos = 0;
    while (( pos = Str.find_first_of( CharsToRemove, pos )) != std::basic_string<T>::npos )
    {
        Str.erase( pos, 1 ); 
    }
}

std::string a ("(555) 555-5555");
Remove( a, "()-");

Works with std::string and std::wstring

Unable to cast object of type 'System.DBNull' to type 'System.String`

I use an extension to eliminate this problem for me, which may or may not be what you are after.

It goes like this:

public static class Extensions
{

    public String TrimString(this object item)
    {
        return String.Format("{0}", item).Trim();
    }

}

Note:

This extension does not return null values! If the item is null or DBNull.Value, it will return an empty String.

Usage:

public string GetCustomerNumber(Guid id)
{
    var obj = 
        DBSqlHelperFactory.ExecuteScalar(
            connectionStringSplendidmyApp, 
            CommandType.StoredProcedure, 
            "GetCustomerNumber", 
            new SqlParameter("@id", id)
        );
    return obj.TrimString();
}

Correct way to synchronize ArrayList in java

You're synchronizing twice, which is pointless and possibly slows down the code: changes while iterating over the list need a synchronnization over the entire operation, which you are doing with synchronized (in_queue_list) Using Collections.synchronizedList() is superfluous in that case (it creates a wrapper that synchronizes individual operations).

However, since you are emptying the list completely, the iterated removal of the first element is the worst possible way to do it, sice for each element all following elements have to be copied, making this an O(n^2) operation - horribly slow for larger lists.

Instead, simply call clear() - no iteration needed.

Edit: If you need the single-method synchronization of Collections.synchronizedList() later on, then this is the correct way:

List<Record> in_queue_list = Collections.synchronizedList(in_queue);
in_queue_list.clear(); // synchronized implicitly, 

But in many cases, the single-method synchronization is insufficient (e.g. for all iteration, or when you get a value, do computations based on it, and replace it with the result). In that case, you have to use manual synchronization anyway, so Collections.synchronizedList() is just useless additional overhead.

Make page to tell browser not to cache/preserve input values

Basically, there are two ways to clear the cache:

<form autocomplete="off"></form>

or

$('#Textfiledid').attr('autocomplete', 'off');

Command to get time in milliseconds

When you use GNU AWK since version 4.1, you can load the time library and do:

$ awk '@load "time"; BEGIN{printf "%.6f", gettimeofday()}'

This will print the current time in seconds since 1970-01-01T00:00:00 in sub second accuracy.

the_time = gettimeofday() Return the time in seconds that has elapsed since 1970-01-01 UTC as a floating-point value. If the time is unavailable on this platform, return -1 and set ERRNO. The returned time should have sub-second precision, but the actual precision may vary based on the platform. If the standard C gettimeofday() system call is available on this platform, then it simply returns the value. Otherwise, if on MS-Windows, it tries to use GetSystemTimeAsFileTime().

source: GNU awk manual

On Linux systems, the standard C function getimeofday() returns the time in microsecond accuracy.

Delete directory with files in it?

What about this:

function recursiveDelete($dirPath, $deleteParent = true){
    foreach(new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dirPath, FilesystemIterator::SKIP_DOTS), RecursiveIteratorIterator::CHILD_FIRST) as $path) {
        $path->isFile() ? unlink($path->getPathname()) : rmdir($path->getPathname());
    }
    if($deleteParent) rmdir($dirPath);
}

List changes unexpectedly after assignment. How do I clone or copy it to prevent this?

It surprises me that this hasn't been mentioned yet, so for the sake of completeness...

You can perform list unpacking with the "splat operator": *, which will also copy elements of your list.

old_list = [1, 2, 3]

new_list = [*old_list]

new_list.append(4)
old_list == [1, 2, 3]
new_list == [1, 2, 3, 4]

The obvious downside to this method is that it is only available in Python 3.5+.

Timing wise though, this appears to perform better than other common methods.

x = [random.random() for _ in range(1000)]

%timeit a = list(x)
%timeit a = x.copy()
%timeit a = x[:]

%timeit a = [*x]

#: 2.47 µs ± 38.1 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
#: 2.47 µs ± 54.6 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
#: 2.39 µs ± 58.2 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)

#: 2.22 µs ± 43.2 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)

Changing the default title of confirm() in JavaScript?

This is not possible, as you say, from a security stand point. The only way you could simulate it, is by creating a modeless dialog window.

There are many third-party javascript-plugins that you could use to fake this effect so you do not have to write all that code.

Get name of current class?

import sys

def class_meta(frame):
    class_context = '__module__' in frame.f_locals
    assert class_context, 'Frame is not a class context'

    module_name = frame.f_locals['__module__']
    class_name = frame.f_code.co_name
    return module_name, class_name

def print_class_path():
    print('%s.%s' % class_meta(sys._getframe(1)))

class MyClass(object):
    print_class_path()

How to describe "object" arguments in jsdoc?

By now there are 4 different ways to document objects as parameters/types. Each has its own uses. Only 3 of them can be used to document return values, though.

For objects with a known set of properties (Variant A)

/**
 * @param {{a: number, b: string, c}} myObj description
 */

This syntax is ideal for objects that are used only as parameters for this function and don't require further description of each property. It can be used for @returns as well.

For objects with a known set of properties (Variant B)

Very useful is the parameters with properties syntax:

/**
 * @param {Object} myObj description
 * @param {number} myObj.a description
 * @param {string} myObj.b description
 * @param {} myObj.c description
 */

This syntax is ideal for objects that are used only as parameters for this function and that require further description of each property. This can not be used for @returns.

For objects that will be used at more than one point in source

In this case a @typedef comes in very handy. You can define the type at one point in your source and use it as a type for @param or @returns or other JSDoc tags that can make use of a type.

/**
 * @typedef {Object} Person
 * @property {string} name how the person is called
 * @property {number} age how many years the person lived
 */

You can then use this in a @param tag:

/**
 * @param {Person} p - Description of p
 */

Or in a @returns:

/**
 * @returns {Person} Description
 */

For objects whose values are all the same type

/**
 * @param {Object.<string, number>} dict
 */

The first type (string) documents the type of the keys which in JavaScript is always a string or at least will always be coerced to a string. The second type (number) is the type of the value; this can be any type. This syntax can be used for @returns as well.

Resources

Useful information about documenting types can be found here:

https://jsdoc.app/tags-type.html

PS:

to document an optional value you can use []:

/**
 * @param {number} [opt_number] this number is optional
 */

or:

/**
 * @param {number|undefined} opt_number this number is optional
 */

What is the javascript filename naming convention?

The question in the link you gave talks about naming of JavaScript variables, not about file naming, so forget about that for the context in which you ask your question.

As to file naming, it is purely a matter of preference and taste. I prefer naming files with hyphens because then I don't have to reach for the shift key, as I do when dealing with camelCase file names; and because I don't have to worry about differences between Windows and Linux file names (Windows file names are case-insensitive, at least through XP).

So the answer, like so many, is "it depends" or "it's up to you."

The one rule you should follow is to be consistent in the convention you choose.

php implode (101) with quotes

Don't know if it's quicker, but, you could save a line of code with your method:

From

$array = array('lastname', 'email', 'phone');
$comma_separated = implode("','", $array);
$comma_separated = "'".$comma_separated."'";

To:

$array = array('lastname', 'email', 'phone');
$comma_separated = "'".implode("','", $array)."'";

For Restful API, can GET method use json data?

To answer your question, yes you may pass JSON in the URI as part of a GET request (provided you URL-encode). However, considering your reason for doing this is due to the length of the URI, using JSON will be self-defeating (introducing more characters than required).

I suggest you send your parameters in body of a POST request, either in regular CGI style (param1=val1&param2=val2) or JSON (parsed by your API upon receipt)

Move all files except one

For bash, sth answer is correct. Here is the zsh (my shell of choice) syntax:

mv ~/Linux/Old/^Tux.png ~/Linux/New/

Requires EXTENDED_GLOB shell option to be set.

Can anyone confirm that phpMyAdmin AllowNoPassword works with MySQL databases?

After lots of struggle I found here you go:

  1. open folder -> xampp
  2. then open -> phpmyadmin
  3. finally open -> config.inc
$cfg['blowfish_secret'] = ''; /* YOU MUST FILL IN THIS FOR COOKIE AUTH! */
  1. Put SHA256 inside single quotations like this one

830bbca930d5e417ae4249931838e2c70ca0365044268fa0ede75e33aff677de

$cfg['blowfish_secret'] = '830bbca930d5e417ae4249931838e2c70ca0365044268fa0ede75e33aff677de
';

I found this when I was downloading updated version of phpmyadmin. I wish this solution help you. enter image description here