Programs & Examples On #Treemaps

Hashing a dictionary?

You could use the third-party frozendict module to freeze your dict and make it hashable.

from frozendict import frozendict
my_dict = frozendict(my_dict)

For handling nested objects, you could go with:

import collections.abc

def make_hashable(x):
    if isinstance(x, collections.abc.Hashable):
        return x
    elif isinstance(x, collections.abc.Sequence):
        return tuple(make_hashable(xi) for xi in x)
    elif isinstance(x, collections.abc.Set):
        return frozenset(make_hashable(xi) for xi in x)
    elif isinstance(x, collections.abc.Mapping):
        return frozendict({k: make_hashable(v) for k, v in x.items()})
    else:
        raise TypeError("Don't know how to make {} objects hashable".format(type(x).__name__))

If you want to support more types, use functools.singledispatch (Python 3.7):

@functools.singledispatch
def make_hashable(x):
    raise TypeError("Don't know how to make {} objects hashable".format(type(x).__name__))

@make_hashable.register
def _(x: collections.abc.Hashable):
    return x

@make_hashable.register
def _(x: collections.abc.Sequence):
    return tuple(make_hashable(xi) for xi in x)

@make_hashable.register
def _(x: collections.abc.Set):
    return frozenset(make_hashable(xi) for xi in x)

@make_hashable.register
def _(x: collections.abc.Mapping):
    return frozendict({k: make_hashable(v) for k, v in x.items()})

# add your own types here

how to make a jquery "$.post" request synchronous

If you want an synchronous request set the async property to false for the request. Check out the jQuery AJAX Doc

Can I convert long to int?

Convert.ToInt32(myValue);

Though I don't know what it will do when it's greater than int.MaxValue.

Finding the handle to a WPF window

Just use your window with the WindowsInteropHelper class:

// ... Window myWindow = get your Window instance...
IntPtr windowHandle = new WindowInteropHelper(myWindow).Handle;

Right now, you're asking for the Application's main window, of which there will always be one. You can use this same technique on any Window, however, provided it is a System.Windows.Window derived Window class.

What does DIM stand for in Visual Basic and BASIC?

Back in the day DIM reserved memory for the array and when memory was limited you had to be careful how you used it. I once wrote (in 1981) a BASIC program on TRS-80 Model III with 48Kb RAM. It wouldn't run on a similar machine with 16Kb RAM until I decreased the array size by changing the DIM statement

ASP.NET MVC Razor: How to render a Razor Partial View's HTML inside the controller action

Borrowing @jgauffin answer as an HtmlHelper extension:

public static class HtmlHelperExtensions
{
    public static MvcHtmlString RenderPartialViewToString(
        this HtmlHelper html, 
        ControllerContext controllerContext, 
        ViewDataDictionary viewData,
        TempDataDictionary tempData,
        string viewName, 
        object model)
    {
        viewData.Model = model;
        string result = String.Empty;

        using (StringWriter sw = new StringWriter())
        {
            ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(controllerContext, viewName);
            ViewContext viewContext = new ViewContext(controllerContext, viewResult.View, viewData, tempData, sw);
            viewResult.View.Render(viewContext, sw);

            result = sw.GetStringBuilder().ToString();
        }

        return MvcHtmlString.Create(result);
    }
}

Usage in a razor view:

Html.RenderPartialViewToString(ViewContext, ViewData, TempData, "Search", Model)

How to check String in response body with mockMvc

@Sotirios Delimanolis answer do the job however I was looking for comparing strings within this mockMvc assertion

So here it is

.andExpect(content().string("\"Username already taken - please try with different username\""));

Of course my assertion fail:

java.lang.AssertionError: Response content expected:
<"Username already taken - please try with different username"> but was:<"Something gone wrong">

because:

  MockHttpServletResponse:
            Body = "Something gone wrong"

So this is proof that it works!

Validate email with a regex in jQuery

This : /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$/i is not working for below Gmail case

[email protected] [email protected]

Below Regex will cover all the E-mail Points: I have tried the all Possible Points and my Test case get also pass because of below regex

I found this Solution from this URL:

Regex Solution link

/(?:((?:[\w-]+(?:\.[\w-]+)*)@(?:(?:[\w-]+\.)*\w[\w-]{0,66})\.(?:[a-z]{2,6}(?:\.[a-z]{2})?));*)/g

How to parse a text file with C#

One way that I've found really useful in situations like this is to go old-school and use the Jet OLEDB provider, together with a schema.ini file to read large tab-delimited files in using ADO.Net. Obviously, this method is really only useful if you know the format of the file to be imported.

public void ImportCsvFile(string filename)
{
    FileInfo file = new FileInfo(filename);

    using (OleDbConnection con = 
            new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\"" +
            file.DirectoryName + "\";
            Extended Properties='text;HDR=Yes;FMT=TabDelimited';"))
    {
        using (OleDbCommand cmd = new OleDbCommand(string.Format
                                  ("SELECT * FROM [{0}]", file.Name), con))
        {
            con.Open();

            // Using a DataReader to process the data
            using (OleDbDataReader reader = cmd.ExecuteReader())
            {
                while (reader.Read())
                {
                    // Process the current reader entry...
                }
            }

            // Using a DataTable to process the data
            using (OleDbDataAdapter adp = new OleDbDataAdapter(cmd))
            {
                DataTable tbl = new DataTable("MyTable");
                adp.Fill(tbl);

                foreach (DataRow row in tbl.Rows)
                {
                    // Process the current row...
                }
            }
        }
    }
} 

Once you have the data in a nice format like a datatable, filtering out the data you need becomes pretty trivial.

How do I add a placeholder on a CharField in Django?

After looking at your method, I used this method to solve it.

class Register(forms.Form):
    username = forms.CharField(label='???', max_length=32)
    email = forms.EmailField(label='??', max_length=64)
    password = forms.CharField(label="??", min_length=6, max_length=16)
    captcha = forms.CharField(label="???", max_length=4)

def __init__(self, *args, **kwargs):
    super().__init__(*args, **kwargs)
    for field_name in self.fields:
        field = self.fields.get(field_name)
        self.fields[field_name].widget.attrs.update({
            "placeholder": field.label,
            'class': "input-control"
        })

How do I check if a C++ std::string starts with a certain string, and convert a substring to an int?

Given that both strings — argv[1] and "--foo" — are C strings, @FelixDombek's answer is hands-down the best solution.

Seeing the other answers, however, I thought it worth noting that, if your text is already available as a std::string, then a simple, zero-copy, maximally efficient solution exists that hasn't been mentioned so far:

const char * foo = "--foo";
if (text.rfind(foo, 0) == 0)
    foo_value = text.substr(strlen(foo));

And if foo is already a string:

std::string foo("--foo");
if (text.rfind(foo, 0) == 0)
    foo_value = text.substr(foo.length());

Bootstrap control with multiple "data-toggle"

If you want to add a modal and a tooltip without adding javascript or altering the tooltip function, you could also simply wrap an element around it:

<span data-toggle="modal" data-target="modal">
    <a data-toggle="tooltip" data-placement="top" title="Tooltip">
      Hover Me           
    </a>
</span>

if checkbox is checked, do this

Why not use the built in events?

$('#checkbox').click(function(e){
    if(e.target.checked) {
     // code to run if checked
        console.log('Checked');

     } else {

     //code to run if unchecked
        console.log('Unchecked');
     }
});

What are the differences between stateless and stateful systems, and how do they impact parallelism?

A stateless system can be seen as a box [black? ;)] where at any point in time the value of the output(s) depends only on the value of the input(s) [after a certain processing time]

A stateful system instead can be seen as a box where at any point in time the value of the output(s) depends on the value of the input(s) and of an internal state, so basicaly a stateful system is like a state machine with "memory" as the same set of input(s) value can generate different output(s) depending on the previous input(s) received by the system.

From the parallel programming point of view, a stateless system, if properly implemented, can be executed by multiple threads/tasks at the same time without any concurrency issue [as an example think of a reentrant function] A stateful system will requires that multiple threads of execution access and update the internal state of the system in an exclusive way, hence there will be a need for a serialization [synchronization] point.

How to connect to a docker container from outside the host (same network) [Windows]

This is the most common issue faced by Windows users for running Docker Containers. IMO this is the "million dollar question on Docker"; @"Rocco Smit" has rightly pointed out "inbound traffic for it was disabled by default on my host machine's firewall"; in my case, my McAfee Anti Virus software. I added additional ports to be allowed for inbound traffic from other computers on the same Wifi LAN in the Firewall Settings of McAfee; then it was magic. I had struggled for more than a week browsing all over internet, SO, Docker documentations, Tutorials after Tutorials related to the Networking of Docker, and the many illustrations of "not supported on Windows" for "macvlan", "ipvlan", "user defined bridge" and even this same SO thread couple of times. I even started browsing google with "anybody using Docker in Production?", (yes I know Linux is more popular for Prod workloads compared to Windows servers) as I was not able to access (from my mobile in the same Home wifi) an nginx app deployed in Docker Container on Windows. After all, what good it is, if you cannot access the application (deployed on a Docker Container) from other computers / devices in the same LAN at-least; Ultimately in my case, the issue was just with a firewall blocking inbound traffic;

MySQL Sum() multiple columns

Another way of doing this is by generating the select query. Play with this fiddle.

SELECT CONCAT('SELECT ', group_concat(`COLUMN_NAME` SEPARATOR '+'), ' FROM scorecard') 
FROM  `INFORMATION_SCHEMA`.`COLUMNS` 
WHERE `TABLE_SCHEMA` = (select database()) 
AND   `TABLE_NAME`   = 'scorecard'
AND   `COLUMN_NAME` LIKE 'mark%';

The query above will generate another query that will do the selecting for you.

  1. Run the above query.
  2. Get the result and run that resulting query.

Sample result:

SELECT mark1+mark2+mark3 FROM scorecard

You won't have to manually add all the columns anymore.

How do I write output in same place on the console?

Use a terminal-handling library like the curses module:

The curses module provides an interface to the curses library, the de-facto standard for portable advanced terminal handling.

Vagrant error : Failed to mount folders in Linux guest

One more step I had to complete after following the first suggestion that kenzie made was to run the mount commands listed in the error message with sudo from the Ubuntu command line [14.04 Server]. After that, everything was good to go!

Two models in one view in ASP MVC 3

Just create a single view Model with all the needed information in it, normaly what I do is create a model for every view so I can be specific on every view, either that or make a parent model and inherit it. OR make a model which includes both the views.

Personally I would just add them into one model but thats the way I do it:

public class xViewModel
{
    public int PersonID { get; set; }
    public string PersonName { get; set; }
    public int OrderID { get; set; }
    public int TotalSum { get; set; }
}

@model project.Models.Home.xViewModel

@using(Html.BeginForm())
{
    @Html.EditorFor(x => x.PersonID)
    @Html.EditorFor(x => x.PersonName)
    @Html.EditorFor(x => x.OrderID)
    @Html.EditorFor(x => x.TotalSum)
}

Round a divided number in Bash

Following worked for me.

 #!/bin/bash
function float() {
bc << EOF
num = $1;
base = num / 1;
if (((num - base) * 10) > 1 )
    base += 1;
print base;
EOF
echo ""
}

float 3.2

Single TextView with multiple colored text

Using Kotlin and Extensions you can add colored text really easy and clean:

Create a file TextViewExtensions.kt with this content

fun TextView.append(string: String?, @ColorRes color: Int) {
    if (string == null || string.isEmpty()) {
        return
    }

    val spannable: Spannable = SpannableString(string)
    spannable.setSpan(
        ForegroundColorSpan(ContextCompat.getColor(context, color)),
        0,
        spannable.length,
        Spannable.SPAN_EXCLUSIVE_EXCLUSIVE
    )

    append(spannable)
}

Now is really easy to append text with color

textView.text = "" // Remove old text
textView.append("Red Text", R.color.colorAccent)
textView.append("White Text", android.R.color.white)

Basically is same as @Abdul Rizwan answer but using Kotlin, extensions, some validations and getting color inside extension.

Can someone provide an example of a $destroy event for scopes in AngularJS?

Demo: http://jsfiddle.net/sunnycpp/u4vjR/2/

Here I have created handle-destroy directive.

ctrl.directive('handleDestroy', function() {
    return function(scope, tElement, attributes) {        
        scope.$on('$destroy', function() {
            alert("In destroy of:" + scope.todo.text);
        });
    };
});

printf with std::string?

The main reason is probably that a C++ string is a struct that includes a current-length value, not just the address of a sequence of chars terminated by a 0 byte. Printf and its relatives expect to find such a sequence, not a struct, and therefore get confused by C++ strings.

Speaking for myself, I believe that printf has a place that can't easily be filled by C++ syntactic features, just as table structures in html have a place that can't easily be filled by divs. As Dykstra wrote later about the goto, he didn't intend to start a religion and was really only arguing against using it as a kludge to make up for poorly-designed code.

It would be quite nice if the GNU project would add the printf family to their g++ extensions.

How can I use the $index inside a ng-repeat to enable a class and show a DIV?

As johnnyynnoj mentioned ng-repeat creates a new scope. I would in fact use a function to set the value. See plunker

JS:

$scope.setSelected = function(selected) {
  $scope.selected = selected;
}

HTML:

{{ selected }}

<ul>
  <li ng-class="{current: selected == 100}">
     <a href ng:click="setSelected(100)">ABC</a>
  </li>
  <li ng-class="{current: selected == 101}">
     <a href ng:click="setSelected(101)">DEF</a>
  </li>
  <li ng-class="{current: selected == $index }" 
      ng-repeat="x in [4,5,6,7]">
     <a href ng:click="setSelected($index)">A{{$index}}</a>
  </li>
</ul>

<div  
  ng:show="selected == 100">
  100        
</div>
<div  
  ng:show="selected == 101">
  101        
</div>
<div ng-repeat="x in [4,5,6,7]" 
  ng:show="selected == $index">
  {{ $index }}        
</div>

Deny direct access to all .php files except index.php

How about keeping all .php-files except for index.php above the web root? No need for any rewrite rules or programmatic kludges.

Adding the includes-folder to your include path will then help to keep things simple, no need to use absolute paths etc.

How to subtract 2 hours from user's local time?

Subtract from another date object

var d = new Date();

d.setHours(d.getHours() - 2);

Loop through JSON object List

var d = $.parseJSON(result.d);
for(var i =0;i<d.length;i++){
    alert(d[i].EmployeeName);
}

php Replacing multiple spaces with a single space

preg_replace("/[[:blank:]]+/"," ",$input)

Developing C# on Linux

You can also install it using conda (tested on Ubuntu):

conda create --name csharp
conda activate csharp
conda install -c conda-forge mono

Pass variables to Ruby script via command line

You can also try out cliqr. Its pretty new and in active development. But there are stable releases ready to be used. Here is the git repo: https://github.com/anshulverma/cliqr

Look into the example folder to get an idea on how it can be used.

SQLPLUS error:ORA-12504: TNS:listener was not given the SERVICE_NAME in CONNECT_DATA

I ran into the exact same problem under identical circumstances. I don't have the tnsnames.ora file, and I wanted to use SQL*Plus with Easy Connection Identifier format in command line. I solved this problem as follows.

The SQL*Plus® User's Guide and Reference gives an example:

sqlplus hr@\"sales-server:1521/sales.us.acme.com\"

Pay attention to two important points:

  1. The connection identifier is quoted. You have two options:
    1. You can use SQL*Plus CONNECT command and simply pass quoted string.
    2. If you want to specify connection parameters on the command line then you must add backslashes as shields before quotes. It instructs the bash to pass quotes into SQL*Plus.
  2. The service name must be specified in FQDN-form as it configured by your DBA.

I found these good questions to detect service name via existing connection: 1, 2. Try this query for example:

SELECT value FROM V$SYSTEM_PARAMETER WHERE UPPER(name) = 'SERVICE_NAMES'

Bind TextBox on Enter-key press

You can make yourself a pure XAML approach by creating an attached behaviour.

Something like this:

public static class InputBindingsManager
{

    public static readonly DependencyProperty UpdatePropertySourceWhenEnterPressedProperty = DependencyProperty.RegisterAttached(
            "UpdatePropertySourceWhenEnterPressed", typeof(DependencyProperty), typeof(InputBindingsManager), new PropertyMetadata(null, OnUpdatePropertySourceWhenEnterPressedPropertyChanged));

    static InputBindingsManager()
    {

    }

    public static void SetUpdatePropertySourceWhenEnterPressed(DependencyObject dp, DependencyProperty value)
    {
        dp.SetValue(UpdatePropertySourceWhenEnterPressedProperty, value);
    }

    public static DependencyProperty GetUpdatePropertySourceWhenEnterPressed(DependencyObject dp)
    {
        return (DependencyProperty)dp.GetValue(UpdatePropertySourceWhenEnterPressedProperty);
    }

    private static void OnUpdatePropertySourceWhenEnterPressedPropertyChanged(DependencyObject dp, DependencyPropertyChangedEventArgs e)
    {
        UIElement element = dp as UIElement;

        if (element == null)
        {
            return;
        }

        if (e.OldValue != null)
        {
            element.PreviewKeyDown -= HandlePreviewKeyDown;
        }

        if (e.NewValue != null)
        {
            element.PreviewKeyDown += new KeyEventHandler(HandlePreviewKeyDown);
        }
    }

    static void HandlePreviewKeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Enter)
        {
            DoUpdateSource(e.Source);
        }
    }

    static void DoUpdateSource(object source)
    {
        DependencyProperty property =
            GetUpdatePropertySourceWhenEnterPressed(source as DependencyObject);

        if (property == null)
        {
            return;
        }

        UIElement elt = source as UIElement;

        if (elt == null)
        {
            return;
        }

        BindingExpression binding = BindingOperations.GetBindingExpression(elt, property);

        if (binding != null)
        {
            binding.UpdateSource();
        }
    }
}

Then in your XAML you set the InputBindingsManager.UpdatePropertySourceWhenEnterPressedProperty property to the one you want updating when the Enter key is pressed. Like this

<TextBox Name="itemNameTextBox"
         Text="{Binding Path=ItemName, UpdateSourceTrigger=PropertyChanged}"
         b:InputBindingsManager.UpdatePropertySourceWhenEnterPressed="TextBox.Text"/>

(You just need to make sure to include an xmlns clr-namespace reference for "b" in the root element of your XAML file pointing to which ever namespace you put the InputBindingsManager in).

jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class

You may find the following windows command line useful in tracking down the offending jar file. it creates an index of all the class files in all the jars in the folder. Execute from within the lib folder of your deployed app, then search the index.txt file for the offending class.

for /r %X in (*.jar) do (echo %X & jar -tf %X) >> index.txt

How do I create a file AND any folders, if the folders don't exist?

You want Directory.CreateDirectory()

Here is a class I use (converted to C#) that if you pass it a source directory and a destination it will copy all of the files and sub-folders of that directory to your destination:

using System.IO;

public class copyTemplateFiles
{


public static bool Copy(string Source, string destination)
{

    try {

        string[] Files = null;

        if (destination[destination.Length - 1] != Path.DirectorySeparatorChar) {
            destination += Path.DirectorySeparatorChar;
        }

        if (!Directory.Exists(destination)) {
            Directory.CreateDirectory(destination);
        }

        Files = Directory.GetFileSystemEntries(Source);
        foreach (string Element in Files) {
            // Sub directories
            if (Directory.Exists(Element)) {
                copyDirectory(Element, destination + Path.GetFileName(Element));
            } else {
                // Files in directory
                File.Copy(Element, destination + Path.GetFileName(Element), true);
            }
        }

    } catch (Exception ex) {
        return false;
    }

    return true;

}



private static void copyDirectory(string Source, string destination)
{
    string[] Files = null;

    if (destination[destination.Length - 1] != Path.DirectorySeparatorChar) {
        destination += Path.DirectorySeparatorChar;
    }

    if (!Directory.Exists(destination)) {
        Directory.CreateDirectory(destination);
    }

    Files = Directory.GetFileSystemEntries(Source);
    foreach (string Element in Files) {
        // Sub directories
        if (Directory.Exists(Element)) {
            copyDirectory(Element, destination + Path.GetFileName(Element));
        } else {
            // Files in directory
            File.Copy(Element, destination + Path.GetFileName(Element), true);
        }
    }

}

}

How to append to New Line in Node.js

It looks like you're running this on Windows (given your H://log.txt file path).

Try using \r\n instead of just \n.

Honestly, \n is fine; you're probably viewing the log file in notepad or something else that doesn't render non-Windows newlines. Try opening it in a different viewer/editor (e.g. Wordpad).

Making TextView scrollable on Android

I had this problem when I was using TextView inside the ScrollView. This solution has worked for me.

scrollView.setOnTouchListener(new View.OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {

                description.getParent().requestDisallowInterceptTouchEvent(false);

                return false;
            }
        });

        description.setOnTouchListener(new View.OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {

                description.getParent().requestDisallowInterceptTouchEvent(true);

                return false;
            }
        });

Get loop count inside a Python FOR loop

I know rather old question but....came across looking other thing so I give my shot:

[each*2 for each in [1,2,3,4,5] if each % 10 == 0])

Test process.env with Jest

In test file:

const APP_PORT = process.env.APP_PORT || 8080;

In the test script of ./package.json:

"scripts": {
   "test": "jest --setupFiles dotenv/config",
 }

In ./env:

APP_PORT=8080

How do I delete a local repository in git?

That's right, if you're on a mac(unix) you won't see .git in finder(the file browser). You can follow the directions above to delete and there are git commands that allow you to delete files as well(they are sometimes difficult to work with and learn, for example: on making a 'git rm -r ' command you might be prompted with a .git/ not found. Here is the git command specs:

usage: git rm [options] [--] ...

-n, --dry-run         dry run
-q, --quiet           do not list removed files
--cached              only remove from the index
-f, --force           override the up-to-date check
-r                    allow recursive removal
--ignore-unmatch      exit with a zero status even if nothing matched

When I had to do this, deleting the objects and refs didn't matter. After I deleted the other files in the .git, I initialized a git repo with 'git init' and it created an empty repo.

How can I see all the "special" characters permissible in a varchar or char field in SQL Server?

You probably just need to see the ASCII and EXTENDED ASCII character sets. As far as I know any of these are allowed in a char/varchar field.

If you use nchar/nvarchar then it's pretty much any character in any unicode set in the world.

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What is RSS and VSZ in Linux memory management

Minimal runnable example

For this to make sense, you have to understand the basics of paging: How does x86 paging work? and in particular that the OS can allocate virtual memory via page tables / its internal memory book keeping (VSZ virtual memory) before it actually has a backing storage on RAM or disk (RSS resident memory).

Now to observe this in action, let's create a program that:

  • allocates more RAM than our physical memory with mmap
  • writes one byte on each page to ensure that each of those pages goes from virtual only memory (VSZ) to actually used memory (RSS)
  • checks the memory usage of the process with one of the methods mentioned at: Memory usage of current process in C

main.c

#define _GNU_SOURCE
#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>

typedef struct {
    unsigned long size,resident,share,text,lib,data,dt;
} ProcStatm;

/* https://stackoverflow.com/questions/1558402/memory-usage-of-current-process-in-c/7212248#7212248 */
void ProcStat_init(ProcStatm *result) {
    const char* statm_path = "/proc/self/statm";
    FILE *f = fopen(statm_path, "r");
    if(!f) {
        perror(statm_path);
        abort();
    }
    if(7 != fscanf(
        f,
        "%lu %lu %lu %lu %lu %lu %lu",
        &(result->size),
        &(result->resident),
        &(result->share),
        &(result->text),
        &(result->lib),
        &(result->data),
        &(result->dt)
    )) {
        perror(statm_path);
        abort();
    }
    fclose(f);
}

int main(int argc, char **argv) {
    ProcStatm proc_statm;
    char *base, *p;
    char system_cmd[1024];
    long page_size;
    size_t i, nbytes, print_interval, bytes_since_last_print;
    int snprintf_return;

    /* Decide how many ints to allocate. */
    if (argc < 2) {
        nbytes = 0x10000;
    } else {
        nbytes = strtoull(argv[1], NULL, 0);
    }
    if (argc < 3) {
        print_interval = 0x1000;
    } else {
        print_interval = strtoull(argv[2], NULL, 0);
    }
    page_size = sysconf(_SC_PAGESIZE);

    /* Allocate the memory. */
    base = mmap(
        NULL,
        nbytes,
        PROT_READ | PROT_WRITE,
        MAP_SHARED | MAP_ANONYMOUS,
        -1,
        0
    );
    if (base == MAP_FAILED) {
        perror("mmap");
        exit(EXIT_FAILURE);
    }

    /* Write to all the allocated pages. */
    i = 0;
    p = base;
    bytes_since_last_print = 0;
    /* Produce the ps command that lists only our VSZ and RSS. */
    snprintf_return = snprintf(
        system_cmd,
        sizeof(system_cmd),
        "ps -o pid,vsz,rss | awk '{if (NR == 1 || $1 == \"%ju\") print}'",
        (uintmax_t)getpid()
    );
    assert(snprintf_return >= 0);
    assert((size_t)snprintf_return < sizeof(system_cmd));
    bytes_since_last_print = print_interval;
    do {
        /* Modify a byte in the page. */
        *p = i;
        p += page_size;
        bytes_since_last_print += page_size;
        /* Print process memory usage every print_interval bytes.
         * We count memory using a few techniques from:
         * https://stackoverflow.com/questions/1558402/memory-usage-of-current-process-in-c */
        if (bytes_since_last_print > print_interval) {
            bytes_since_last_print -= print_interval;
            printf("extra_memory_committed %lu KiB\n", (i * page_size) / 1024);
            ProcStat_init(&proc_statm);
            /* Check /proc/self/statm */
            printf(
                "/proc/self/statm size resident %lu %lu KiB\n",
                (proc_statm.size * page_size) / 1024,
                (proc_statm.resident * page_size) / 1024
            );
            /* Check ps. */
            puts(system_cmd);
            system(system_cmd);
            puts("");
        }
        i++;
    } while (p < base + nbytes);

    /* Cleanup. */
    munmap(base, nbytes);
    return EXIT_SUCCESS;
}

GitHub upstream.

Compile and run:

gcc -ggdb3 -O0 -std=c99 -Wall -Wextra -pedantic -o main.out main.c
echo 1 | sudo tee /proc/sys/vm/overcommit_memory
sudo dmesg -c
./main.out 0x1000000000 0x200000000
echo $?
sudo dmesg

where:

  • 0x1000000000 == 64GiB: 2x my computer's physical RAM of 32GiB
  • 0x200000000 == 8GiB: print the memory every 8GiB, so we should get 4 prints before the crash at around 32GiB
  • echo 1 | sudo tee /proc/sys/vm/overcommit_memory: required for Linux to allow us to make a mmap call larger than physical RAM: maximum memory which malloc can allocate

Program output:

extra_memory_committed 0 KiB
/proc/self/statm size resident 67111332 768 KiB
ps -o pid,vsz,rss | awk '{if (NR == 1 || $1 == "29827") print}'
  PID    VSZ   RSS
29827 67111332 1648

extra_memory_committed 8388608 KiB
/proc/self/statm size resident 67111332 8390244 KiB
ps -o pid,vsz,rss | awk '{if (NR == 1 || $1 == "29827") print}'
  PID    VSZ   RSS
29827 67111332 8390256

extra_memory_committed 16777216 KiB
/proc/self/statm size resident 67111332 16778852 KiB
ps -o pid,vsz,rss | awk '{if (NR == 1 || $1 == "29827") print}'
  PID    VSZ   RSS
29827 67111332 16778864

extra_memory_committed 25165824 KiB
/proc/self/statm size resident 67111332 25167460 KiB
ps -o pid,vsz,rss | awk '{if (NR == 1 || $1 == "29827") print}'
  PID    VSZ   RSS
29827 67111332 25167472

Killed

Exit status:

137

which by the 128 + signal number rule means we got signal number 9, which man 7 signal says is SIGKILL, which is sent by the Linux out-of-memory killer.

Output interpretation:

  • VSZ virtual memory remains constant at printf '0x%X\n' 0x40009A4 KiB ~= 64GiB (ps values are in KiB) after the mmap.
  • RSS "real memory usage" increases lazily only as we touch the pages. For example:
    • on the first print, we have extra_memory_committed 0, which means we haven't yet touched any pages. RSS is a small 1648 KiB which has been allocated for normal program startup like text area, globals, etc.
    • on the second print, we have written to 8388608 KiB == 8GiB worth of pages. As a result, RSS increased by exactly 8GIB to 8390256 KiB == 8388608 KiB + 1648 KiB
    • RSS continues to increase in 8GiB increments. The last print shows about 24 GiB of memory, and before 32 GiB could be printed, the OOM killer killed the process

See also: https://unix.stackexchange.com/questions/35129/need-explanation-on-resident-set-size-virtual-size

OOM killer logs

Our dmesg commands have shown the OOM killer logs.

An exact interpretation of those has been asked at:

The very first line of the log was:

[ 7283.479087] mongod invoked oom-killer: gfp_mask=0x6200ca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=0

So we see that interestingly it was the MongoDB daemon that always runs in my laptop on the background that first triggered the OOM killer, presumably when the poor thing was trying to allocate some memory.

However, the OOM killer does not necessarily kill the one who awoke it.

After the invocation, the kernel prints a table or processes including the oom_score:

[ 7283.479292] [  pid  ]   uid  tgid total_vm      rss pgtables_bytes swapents oom_score_adj name
[ 7283.479303] [    496]     0   496    16126        6   172032      484             0 systemd-journal
[ 7283.479306] [    505]     0   505     1309        0    45056       52             0 blkmapd
[ 7283.479309] [    513]     0   513    19757        0    57344       55             0 lvmetad
[ 7283.479312] [    516]     0   516     4681        1    61440      444         -1000 systemd-udevd

and further ahead we see that our own little main.out actually got killed on the previous invocation:

[ 7283.479871] Out of memory: Kill process 15665 (main.out) score 865 or sacrifice child
[ 7283.479879] Killed process 15665 (main.out) total-vm:67111332kB, anon-rss:92kB, file-rss:4kB, shmem-rss:30080832kB
[ 7283.479951] oom_reaper: reaped process 15665 (main.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:30080832kB

This log mentions the score 865 which that process had, presumably the highest (worst) OOM killer score as mentioned at: https://unix.stackexchange.com/questions/153585/how-does-the-oom-killer-decide-which-process-to-kill-first

Also interestingly, everything apparently happened so fast that before the freed memory was accounted, the oom was awoken again by the DeadlineMonitor process:

[ 7283.481043] DeadlineMonitor invoked oom-killer: gfp_mask=0x6200ca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=0

and this time that killed some Chromium process, which is usually my computers normal memory hog:

[ 7283.481773] Out of memory: Kill process 11786 (chromium-browse) score 306 or sacrifice child
[ 7283.481833] Killed process 11786 (chromium-browse) total-vm:1813576kB, anon-rss:208804kB, file-rss:0kB, shmem-rss:8380kB
[ 7283.497847] oom_reaper: reaped process 11786 (chromium-browse), now anon-rss:0kB, file-rss:0kB, shmem-rss:8044kB

Tested in Ubuntu 19.04, Linux kernel 5.0.0.

How can I use a DLL file from Python?

ctypes will be the easiest thing to use but (mis)using it makes Python subject to crashing. If you are trying to do something quickly, and you are careful, it's great.

I would encourage you to check out Boost Python. Yes, it requires that you write some C++ code and have a C++ compiler, but you don't actually need to learn C++ to use it, and you can get a free (as in beer) C++ compiler from Microsoft.

Timeout a command in bash without unnecessary delay

timeout is probably the first approach to try. You may need notification or another command to execute if it times out. After quite a bit of searching and experimenting, I came up with this bash script:

if 
    timeout 20s COMMAND_YOU_WANT_TO_EXECUTE;
    timeout 20s AS_MANY_COMMANDS_AS_YOU_WANT;
then
    echo 'OK'; #if you want a positive response
else
    echo 'Not OK';
    AND_ALTERNATIVE_COMMANDS
fi

Windows Scipy Install: No Lapack/Blas Resources Found

This was the order I got everything working. The second point is the most important one. Scipy needs Numpy+MKL, not just vanilla Numpy.

  1. Install python 3.5
  2. pip install "file path" (download Numpy+MKL wheel from here http://www.lfd.uci.edu/~gohlke/pythonlibs/#numpy)
  3. pip install scipy

How to handle an IF STATEMENT in a Mustache template?

Just took a look over the mustache docs and they support "inverted sections" in which they state

they (inverted sections) will be rendered if the key doesn't exist, is false, or is an empty list

http://mustache.github.io/mustache.5.html#Inverted-Sections

{{#value}}
  value is true
{{/value}}
{{^value}}
  value is false
{{/value}}

How to delete a row from GridView?

Please try this code.....

DataRow dr = dtPrf_Mstr.NewRow();
dtPrf_Mstr.Rows.Add(dr);
GVGLCode.DataSource = dtPrf_Mstr;
GVGLCode.DataBind();
int iCount = GVGLCode.Rows.Count;
for (int i = 0; i < iCount; i++)
{
   GVGLCode.Rows.Remove(GVGLCode.Rows[i]);
}
GVGLCode.DataBind();

SQL Server 2008 R2 can't connect to local database in Management Studio

If your instance is called SQLEXPRESS, then you need to use .\SQLEXPRESS or (local)\SQLEXPRESS or yourMachineName\SQLEXPRESS as your server name - if you have a named instance, you need to specify that name of the instance in your server name.

Python: count repeated elements in the list

This works for Python 2.6.6

a = ["a", "b", "a"]
result = dict((i, a.count(i)) for i in a)
print result

prints

{'a': 2, 'b': 1}

node.js + mysql connection pooling

You should avoid using pool.getConnection() if you can. If you call pool.getConnection(), you must call connection.release() when you are done using the connection. Otherwise, your application will get stuck waiting forever for connections to be returned to the pool once you hit the connection limit.

For simple queries, you can use pool.query(). This shorthand will automatically call connection.release() for you—even in error conditions.

function doSomething(cb) {
  pool.query('SELECT 2*2 "value"', (ex, rows) => {
    if (ex) {
      cb(ex);
    } else {
      cb(null, rows[0].value);
    }
  });
}

However, in some cases you must use pool.getConnection(). These cases include:

  • Making multiple queries within a transaction.
  • Sharing data objects such as temporary tables between subsequent queries.

If you must use pool.getConnection(), ensure you call connection.release() using a pattern similar to below:

function doSomething(cb) {
  pool.getConnection((ex, connection) => {
    if (ex) {
      cb(ex);
    } else {
      // Ensure that any call to cb releases the connection
      // by wrapping it.
      cb = (cb => {
        return function () {
          connection.release();
          cb.apply(this, arguments);
        };
      })(cb);
      connection.beginTransaction(ex => {
        if (ex) {
          cb(ex);
        } else {
          connection.query('INSERT INTO table1 ("value") VALUES (\'my value\');', ex => {
            if (ex) {
              cb(ex);
            } else {
              connection.query('INSERT INTO table2 ("value") VALUES (\'my other value\')', ex => {
                if (ex) {
                  cb(ex);
                } else {
                  connection.commit(ex => {
                    cb(ex);
                  });
                }
              });
            }
          });
        }
      });
    }
  });
}

I personally prefer to use Promises and the useAsync() pattern. This pattern combined with async/await makes it a lot harder to accidentally forget to release() the connection because it turns your lexical scoping into an automatic call to .release():

async function usePooledConnectionAsync(actionAsync) {
  const connection = await new Promise((resolve, reject) => {
    pool.getConnection((ex, connection) => {
      if (ex) {
        reject(ex);
      } else {
        resolve(connection);
      }
    });
  });
  try {
    return await actionAsync(connection);
  } finally {
    connection.release();
  }
}

async function doSomethingElse() {
  // Usage example:
  const result = await usePooledConnectionAsync(async connection => {
    const rows = await new Promise((resolve, reject) => {
      connection.query('SELECT 2*4 "value"', (ex, rows) => {
        if (ex) {
          reject(ex);
        } else {
          resolve(rows);
        }
      });
    });
    return rows[0].value;
  });
  console.log(`result=${result}`);
}

SQL Column definition : default value and not null redundant?

I would say not.

If the column does accept null values, then there's nothing to stop you inserting a null value into the field. As far as I'm aware, the default value only applies on creation of a new row.

With not null set, then you can't insert a null value into the field as it'll throw an error.

Think of it as a fail safe mechanism to prevent nulls.

Joining two lists together

one way: List.AddRange() depending on the types?

Set folder browser dialog start location

Set the SelectedPath property before you call ShowDialog ...

folderBrowserDialog1.SelectedPath = @"c:\temp\";
folderBrowserDialog1.ShowDialog();

Will start them at C:\Temp

pip install returning invalid syntax

try this.

python -m  pip ...

-m module-name Searches sys.path for the named module and runs the corresponding .py file as a script.

Sometimes the OS can't find pip so python or py -m may solve the problem because it is python itself searching for pip.

Add new field to every document in a MongoDB collection

Pymongo 3.9+

update() is now deprecated and you should use replace_one(), update_one(), or update_many() instead.

In my case I used update_many() and it solved my issue:

db.your_collection.update_many({}, {"$set": {"new_field": "value"}}, upsert=False, array_filters=None)

From documents

update_many(filter, update, upsert=False, array_filters=None, bypass_document_validation=False, collation=None, session=None)


filter: A query that matches the documents to update.

update: The modifications to apply.

upsert (optional): If True, perform an insert if no documents match the filter.

bypass_document_validation (optional): If True, allows the write to opt-out of document level validation. Default is False.

collation (optional): An instance of Collation. This option is only supported on MongoDB 3.4 and above.

array_filters (optional): A list of filters specifying which array elements an update should apply. Requires MongoDB 3.6+.

session (optional): a ClientSession.

How to remove "onclick" with JQuery?

It is very easy using removeAttr.

$(element).removeAttr("onclick");

Basic authentication for REST API using spring restTemplate

You may use spring-boot RestTemplateBuilder

@Bean
RestOperations rest(RestTemplateBuilder restTemplateBuilder) {
    return restTemplateBuilder.basicAuthentication("user", "password").build();
}

See documentation

(before SB 2.1.0 it was #basicAuthorization)

Why can't static methods be abstract in Java?

As per Java doc:

A static method is a method that is associated with the class in which it is defined rather than with any object. Every instance of the class shares its static methods

In Java 8, along with default methods static methods are also allowed in an interface. This makes it easier for us to organize helper methods in our libraries. We can keep static methods specific to an interface in the same interface rather than in a separate class.

A nice example of this is:

list.sort(ordering);

instead of

Collections.sort(list, ordering);

Another example of using static methods is also given in doc itself:

public interface TimeClient {
    // ...
    static public ZoneId getZoneId (String zoneString) {
        try {
            return ZoneId.of(zoneString);
        } catch (DateTimeException e) {
            System.err.println("Invalid time zone: " + zoneString +
                "; using default time zone instead.");
            return ZoneId.systemDefault();
        }
    }

    default public ZonedDateTime getZonedDateTime(String zoneString) {
        return ZonedDateTime.of(getLocalDateTime(), getZoneId(zoneString));
    }    
}

Request failed: unacceptable content-type: text/html using AFNetworking 2.0

I had a somehow similar problem working with AFNetworking from a Swift codebase so I'm just leaving this here in the remote case someone is as unlucky as me having to work in such a setup. If you are, I feel you buddy, stay strong!

The operation was failing due to "unacceptable content-type", despite me actually setting the acceptableContentTypes with a Set containing the content type value in question.

The solution for me was to tweak the Swift code to be more Objective-C friendly, I guess:

serializer.acceptableContentTypes = NSSet(array: ["application/xml", "text/xml", "text/plain"]) as Set<NSObject>

Keras, How to get the output of each layer?

Assuming you have:

1- Keras pre-trained model.

2- Input x as image or set of images. The resolution of image should be compatible with dimension of the input layer. For example 80*80*3 for 3-channels (RGB) image.

3- The name of the output layer to get the activation. For example, "flatten_2" layer. This should be include in the layer_names variable, represents name of layers of the given model.

4- batch_size is an optional argument.

Then you can easily use get_activation function to get the activation of the output layer for a given input x and pre-trained model:

import six
import numpy as np
import keras.backend as k
from numpy import float32
def get_activations(x, model, layer, batch_size=128):
"""
Return the output of the specified layer for input `x`. `layer` is specified by layer index (between 0 and
`nb_layers - 1`) or by name. The number of layers can be determined by counting the results returned by
calling `layer_names`.
:param x: Input for computing the activations.
:type x: `np.ndarray`. Example: x.shape = (80, 80, 3)
:param model: pre-trained Keras model. Including weights.
:type model: keras.engine.sequential.Sequential. Example: model.input_shape = (None, 80, 80, 3)
:param layer: Layer for computing the activations
:type layer: `int` or `str`. Example: layer = 'flatten_2'
:param batch_size: Size of batches.
:type batch_size: `int`
:return: The output of `layer`, where the first dimension is the batch size corresponding to `x`.
:rtype: `np.ndarray`. Example: activations.shape = (1, 2000)
"""

    layer_names = [layer.name for layer in model.layers]
    if isinstance(layer, six.string_types):
        if layer not in layer_names:
            raise ValueError('Layer name %s is not part of the graph.' % layer)
        layer_name = layer
    elif isinstance(layer, int):
        if layer < 0 or layer >= len(layer_names):
            raise ValueError('Layer index %d is outside of range (0 to %d included).'
                             % (layer, len(layer_names) - 1))
        layer_name = layer_names[layer]
    else:
        raise TypeError('Layer must be of type `str` or `int`.')

    layer_output = model.get_layer(layer_name).output
    layer_input = model.input
    output_func = k.function([layer_input], [layer_output])

    # Apply preprocessing
    if x.shape == k.int_shape(model.input)[1:]:
        x_preproc = np.expand_dims(x, 0)
    else:
        x_preproc = x
    assert len(x_preproc.shape) == 4

    # Determine shape of expected output and prepare array
    output_shape = output_func([x_preproc[0][None, ...]])[0].shape
    activations = np.zeros((x_preproc.shape[0],) + output_shape[1:], dtype=float32)

    # Get activations with batching
    for batch_index in range(int(np.ceil(x_preproc.shape[0] / float(batch_size)))):
        begin, end = batch_index * batch_size, min((batch_index + 1) * batch_size, x_preproc.shape[0])
        activations[begin:end] = output_func([x_preproc[begin:end]])[0]

    return activations

You have not accepted the license agreements of the following SDK components

Update for macOS Sierra 10.12.6 - Android Studio for Mac 2.3.3

Locate the sdkmanager file usually under:

/Users/YOUR_MAC_USER/Library/Android/sdk/tools/bin

./sdkmanager --licenses

Warning: File /Users/mtro.josevaler**strong text**io/.android/repositories.cfg could not be loaded. 6 of 6 SDK package licenses not accepted. Review licenses that have not been accepted (y/N)? Y

To validate the problem has gone just repeat the operation involved in the license issue.

php $_GET and undefined index

Avoid if, else and elseifs!

$loadMethod = "";
if(isset($_GET['s'])){
    switch($_GET['s']){
        case 'jwshxnsyllabus':
            $loadMethod = "loadSyllabi('syllabus', '../syllabi/jwshxnporsyllabus.xml', '../bibliographies/jwshxnbibliography_')";
        break;
        case 'aquinas':
            $loadMethod = "loadSyllabi('syllabus', '../syllabi/AquinasSyllabus.xml')";
        break;
        case 'POP2':
            $loadMethod = "loadSyllabi('POP2')";
    }
}

echo '<body onload="'.$loadMethod.'">';

clean, readable code is maintainable code

How to split page into 4 equal parts?

Some good answers here but just adding an approach that won't be affected by borders and padding:

<style type="text/css">
html, body{width: 100%; height: 100%; padding: 0; margin: 0}
div{position: absolute; padding: 1em; border: 1px solid #000}
#nw{background: #f09; top: 0; left: 0; right: 50%; bottom: 50%}
#ne{background: #f90; top: 0; left: 50%; right: 0; bottom: 50%}
#sw{background: #009; top: 50%; left: 0; right: 50%; bottom: 0}
#se{background: #090; top: 50%; left: 50%; right: 0; bottom: 0}
</style>

<div id="nw">test</div>
<div id="ne">test</div>
<div id="sw">test</div>
<div id="se">test</div>

How do I apply a CSS class to Html.ActionLink in ASP.NET MVC?

In VB.NET

<%=Html.ActionLink("Contact Us", "ContactUs", "Home", Nothing, New With {.class = "link"})%>

This will assign css class "link" to the Contact Us.

This will generate following HTML :

<a class="link" href="www.domain.com/Home/ContactUs">Contact Us</a>

C - The %x format specifier

From http://en.wikipedia.org/wiki/Printf_format_string

use 0 instead of spaces to pad a field when the width option is specified. For example, printf("%2d", 3) results in " 3", while printf("%02d", 3) results in "03".

Moment get current date

Just call moment as a function without any arguments:

moment()

For timezone information with moment, look at the moment-timezone package: http://momentjs.com/timezone/

How to create a link to another PHP page

echo "<a href='index.php'>Index Page</a>";

if you wanna use html tag like anchor tag you have to put in echo

Run a Python script from another Python script, passing in arguments

Ideally, the Python script you want to run will be set up with code like this near the end:

def main(arg1, arg2, etc):
    # do whatever the script does


if __name__ == "__main__":
    main(sys.argv[1], sys.argv[2], sys.argv[3])

In other words, if the module is called from the command line, it parses the command line options and then calls another function, main(), to do the actual work. (The actual arguments will vary, and the parsing may be more involved.)

If you want to call such a script from another Python script, however, you can simply import it and call modulename.main() directly, rather than going through the operating system.

os.system will work, but it is the roundabout (read "slow") way to do it, as you are starting a whole new Python interpreter process each time for no raisin.

"Unmappable character for encoding UTF-8" error

The Java compiler assumes that your input is UTF-8 encoded, either because you specified it to be or because it's your platform default encoding.

However, the data in your .java files is not actually encoded in UTF-8. The problem is probably the ¬ character. Make sure your editor (or IDE) of choice actually safes its file in UTF-8 encoding.

How do I use a delimiter with Scanner.useDelimiter in Java?

For example:

String myInput = null;
Scanner myscan = new Scanner(System.in).useDelimiter("\\n");
System.out.println("Enter your input: ");
myInput = myscan.next();
System.out.println(myInput);

This will let you use Enter as a delimiter.

Thus, if you input:

Hello world (ENTER)

it will print 'Hello World'.

How can I fetch all items from a DynamoDB table without specifying the primary key?

I figured you are using PHP but not mentioned (edited). I found this question by searching internet and since I got solution working , for those who use nodejs here is a simple solution using scan :

  var dynamoClient = new AWS.DynamoDB.DocumentClient();
  var params = {
    TableName: config.dynamoClient.tableName, // give it your table name 
    Select: "ALL_ATTRIBUTES"
  };

  dynamoClient.scan(params, function(err, data) {
    if (err) {
       console.error("Unable to read item. Error JSON:", JSON.stringify(err, null, 2));
    } else {
       console.log("GetItem succeeded:", JSON.stringify(data, null, 2));
    }
  });

I assume same code can be translated to PHP too using different AWS SDK

Split string in C every white space

Consider using strtok_r, as others have suggested, or something like:

void printWords(const char *string) {
    // Make a local copy of the string that we can manipulate.
    char * const copy = strdup(string);
    char *space = copy;
    // Find the next space in the string, and replace it with a newline.
    while (space = strchr(space,' ')) *space = '\n';
    // There are no more spaces in the string; print out our modified copy.
    printf("%s\n", copy);
    // Free our local copy
    free(copy);
}

How to export a mysql database using Command Prompt?

mysql -u -p databaseName>fileToPutDatabase

Filter Pyspark dataframe column with None value

None/Null is a data type of the class NoneType in pyspark/python so, Below will not work as you are trying to compare NoneType object with string object

Wrong way of filreting

df[df.dt_mvmt == None].count() 0 df[df.dt_mvmt != None].count() 0

correct

df=df.where(col("dt_mvmt").isNotNull()) returns all records with dt_mvmt as None/Null

Convert object to JSON in Android

public class Producto {

int idProducto;
String nombre;
Double precio;



public Producto(int idProducto, String nombre, Double precio) {

    this.idProducto = idProducto;
    this.nombre = nombre;
    this.precio = precio;

}
public int getIdProducto() {
    return idProducto;
}
public void setIdProducto(int idProducto) {
    this.idProducto = idProducto;
}
public String getNombre() {
    return nombre;
}
public void setNombre(String nombre) {
    this.nombre = nombre;
}
public Double getPrecio() {
    return precio;
}
public void setPrecio(Double precio) {
    this.precio = precio;
}

public String toJSON(){

    JSONObject jsonObject= new JSONObject();
    try {
        jsonObject.put("id", getIdProducto());
        jsonObject.put("nombre", getNombre());
        jsonObject.put("precio", getPrecio());

        return jsonObject.toString();
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        return "";
    }

}

Check that a input to UITextField is numeric only

In Swift 4:

let formatString = "12345"
if let number = Decimal(string:formatString){

    print("String contains only number")
}
else{
    print("String doesn't contains only number")
}

Can't bind to 'ngIf' since it isn't a known property of 'div'

Just for anyone who still has an issue, I also had an issue where I typed ngif rather than ngIf (notice the capital 'I').

How to list all users in a Linux group?

just a little grep and tr:

$ grep ^$GROUP /etc/group | grep -o '[^:]*$' | tr ',' '\n'
user1
user2
user3

Transpose list of lists

Three options to choose from:

1. Map with Zip

solution1 = map(list, zip(*l))

2. List Comprehension

solution2 = [list(i) for i in zip(*l)]

3. For Loop Appending

solution3 = []
for i in zip(*l):
    solution3.append((list(i)))

And to view the results:

print(*solution1)
print(*solution2)
print(*solution3)

# [1, 4, 7], [2, 5, 8], [3, 6, 9]

How do I remove/delete a virtualenv?

from virtualenv's official document https://virtualenv.pypa.io/en/stable/userguide/

Removing an Environment

Removing a virtual environment is simply done by deactivating it and deleting the environment folder with all its contents:

(ENV)$ deactivate
$ rm -r /path/to/ENV

How to keep form values after post

If you are looking to just repopulate the fields with the values that were posted in them, then just echo the post value back into the field, like so:

<input type="text" name="myField1" value="<?php echo isset($_POST['myField1']) ? $_POST['myField1'] : '' ?>" />

Why GDB jumps unpredictably between lines and prints variables as "<value optimized out>"?

To debug optimized code, learn assembly/machine language.

Use the GDB TUI mode. My copy of GDB enables it when I type the minus and Enter. Then type C-x 2 (that is hold down Control and press X, release both and then press 2). That will put it into split source and disassembly display. Then use stepi and nexti to move one machine instruction at a time. Use C-x o to switch between the TUI windows.

Download a PDF about your CPU's machine language and the function calling conventions. You will quickly learn to recognize what is being done with function arguments and return values.

You can display the value of a register by using a GDB command like p $eax

How do I bottom-align grid elements in bootstrap fluid layout

Well, I didn't like any of those answers, my solution of the same problem was to add this:<div>&nbsp;</div>. So in your scheme it would look like this (more or less), no style changes were necessary in my case:

-row-fluid-------------------------------------
+-span6----------+ +----span6----------+
|                | | +---div---+       |
| content        | | | & nbsp; |       |
| that           | | +---------+       |
| is tall        | | +-----div--------+|   
|                | | |short content   ||
|                | | +----------------+|
+----------------+ +-------------------+
-----------------------------------------------

Difference between DOM parentNode and parentElement

Just like with nextSibling and nextElementSibling, just remember that, properties with "element" in their name always returns Element or null. Properties without can return any other kind of node.

console.log(document.body.parentNode, "is body's parent node");    // returns <html>
console.log(document.body.parentElement, "is body's parent element"); // returns <html>

var html = document.body.parentElement;
console.log(html.parentNode, "is html's parent node"); // returns document
console.log(html.parentElement, "is html's parent element"); // returns null

Pipe to/from the clipboard in Bash script

There are different clipboards in Linux; the X server has one, the window manager might have another one, etc. There is no standard device.

Oh, yes, on CLI, the screen program has its own clipboard as well, as do some other applications like Emacs and vi.

In X, you can use xclip.

You can check this thread for other possible answers: http://unix.derkeiler.com/Newsgroups/comp.unix.shell/2004-07/0919.html

Where are environment variables stored in the Windows Registry?

I always had problems with that, and I made a getx.bat script:

:: getx %envvar% [\m]
:: Reads envvar from user environment variable and stores it in the getxvalue variable
:: with \m read system environment

@SETLOCAL EnableDelayedExpansion
@echo OFF

@set l_regpath="HKEY_CURRENT_USER\Environment"
@if "\m"=="%2" set l_regpath="HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment"

::REG ADD "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v PATH /t REG_SZ /f /d "%PATH%"
::@REG QUERY %l_regpath% /v %1 /S

@FOR /F "tokens=*" %%A IN ('REG QUERY %l_regpath% /v %1 /S') DO (
@  set l_a=%%A
@    if NOT "!l_a!"=="!l_a:    =!" set l_line=!l_a!
)

:: Delimiter is four spaces. Change it to tab \t
@set l_line=!l_line!
@set l_line=%l_line:    =    %

@set getxvalue=

@FOR /F "tokens=3* delims=  " %%A IN ("%l_line%") DO (
@    set getxvalue=%%A
)
@set getxvalue=!getxvalue!
@echo %getxvalue% > getxfile.tmp.txt
@ENDLOCAL

:: We already used tab as a delimiter
@FOR /F "delims=    " %%A IN (getxfile.tmp.txt) DO (
    @set getxvalue=%%A
)
@del getxfile.tmp.txt

@echo ON

GridView sorting: SortDirection always Ascending

Using SecretSquirrel's solution above

here is my full working, production code. Just change dgvCoaches to your grid view name.

... during the binding of the grid

        dgvCoaches.DataSource = dsCoaches.Tables[0];
        ViewState["AllCoaches"] = dsCoaches.Tables[0];
        dgvCoaches.DataBind();

and now the sorting

protected void gridView_Sorting(object sender, GridViewSortEventArgs e)
{
    DataTable dt = ViewState["AllCoaches"] as DataTable;

    if (dt != null)
    {
        if (e.SortExpression == (string)ViewState["SortColumn"])
        {
            // We are resorting the same column, so flip the sort direction
            e.SortDirection =
                ((SortDirection)ViewState["SortColumnDirection"] == SortDirection.Ascending) ?
                SortDirection.Descending : SortDirection.Ascending;
        }
        // Apply the sort
        dt.DefaultView.Sort = e.SortExpression +
            (string)((e.SortDirection == SortDirection.Ascending) ? " ASC" : " DESC");
        ViewState["SortColumn"] = e.SortExpression;
        ViewState["SortColumnDirection"] = e.SortDirection; 

        dgvCoaches.DataSource = dt;
        dgvCoaches.DataBind();
    }
}

and here is the aspx code:

<asp:GridView ID="dgvCoaches" runat="server" 
    CssClass="table table-hover table-striped" GridLines="None"  DataKeyNames="HealthCoachID" OnRowCommand="dgvCoaches_RowCommand"
    AutoGenerateColumns="False" OnSorting="gridView_Sorting" AllowSorting="true">
    <Columns>
        <asp:BoundField DataField="HealthCoachID" Visible="false" />
        <asp:BoundField DataField="LastName" HeaderText="Last Name" SortExpression="LastName" />
        <asp:BoundField DataField="FirstName" HeaderText="First Name" SortExpression="FirstName" />
        <asp:BoundField DataField="LoginName" HeaderText="Login Name" SortExpression="LoginName" />
        <asp:BoundField DataField="Email" HeaderText="Email" SortExpression="Email" HtmlEncode="false" DataFormatString="<a href=mailto:{0}>{0}</a>" />
        <asp:TemplateField>
            <ItemTemplate>
                    <asp:LinkButton runat="server" BorderStyle="None" CssClass="btn btn-default" Text="<i class='glyphicon glyphicon-edit'></i>" CommandName="Update" CommandArgument="<%# ((GridViewRow) Container).RowIndex %>" />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:LinkButton runat="server" OnClientClick="return ConfirmOnDelete();" BorderStyle="None" CssClass="btn btn-default" Text="<i class='glyphicon glyphicon-remove'></i>" CommandName="Delete" CommandArgument="<%# ((GridViewRow) Container).RowIndex %>" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
    <RowStyle CssClass="cursor-pointer" />
</asp:GridView>

SHA1 vs md5 vs SHA256: which to use for a PHP login?

I think using md5 or sha256 or any hash optimized for speed is perfectly fine and am very curious to hear any rebuttle other users might have. Here are my reasons

  1. If you allow users to use weak passwords such as God, love, war, peace then no matter the encryption you will still be allowing the user to type in the password not the hash and these passwords are often used first, thus this is NOT going to have anything to do with encryption.

  2. If your not using SSL or do not have a certificate then attackers listening to the traffic will be able to pull the password and any attempts at encrypting with javascript or the like is client side and easily cracked and overcome. Again this is NOT going to have anything to do with data encryption on server side.

  3. Brute force attacks will take advantage weak passwords and again because you allow the user to enter the data if you do not have the login limitation of 3 or even a little more then the problem will again NOT have anything to do with data encryption.

  4. If your database becomes compromised then most likely everything has been compromised including your hashing techniques no matter how cryptic you've made it. Again this could be a disgruntled employee XSS attack or sql injection or some other attack that has nothing to do with your password encryption.

I do believe you should still encrypt but the only thing I can see the encryption does is prevent people that already have or somehow gained access to the database from just reading out loud the password. If it is someone unauthorized to on the database then you have bigger issues to worry about that's why Sony got took because they thought an encrypted password protected everything including credit card numbers all it does is protect that one field that's it.

The only pure benefit I can see to complex encryptions of passwords in a database is to delay employees or other people that have access to the database from just reading out the passwords. So if it's a small project or something I wouldn't worry to much about security on the server side instead I would worry more about securing anything a client might send to the server such as sql injection, XSS attacks or the plethora of other ways you could be compromised. If someone disagrees I look forward to reading a way that a super encrypted password is a must from the client side.

The reason I wanted to try and make this clear is because too often people believe an encrypted password means they don't have to worry about it being compromised and they quit worrying about securing the website.

Loop X number of times

Use:

1..10 | % { write "loop $_" }

Output:

PS D:\temp> 1..10 | % { write "loop $_" }
loop 1
loop 2
loop 3
loop 4
loop 5
loop 6
loop 7
loop 8
loop 9
loop 10

ffprobe or avprobe not found. Please install one

This is an old question. But if you're using a virtualenv with python, place the contents of the downloaded libav bin folder in the Scriptsfolder of your virtualenv.

Javascript: Call a function after specific time period

Timeout:

setTimeout(() => {
   console.log('Hello Timeout!')
}, 3000);

Interval:

setInterval(() => {
   console.log('Hello Interval!')
}, 2000);

How to add a classname/id to React-Bootstrap Component?

If you look at the code for the component you can see that it uses the className prop passed to it to combine with the row class to get the resulting set of classes (<Row className="aaa bbb"... works).Also, if you provide the id prop like <Row id="444" ... it will actually set the id attribute for the element.

Android studio Error "Unsupported Modules Detected: Compilation is not supported for following modules"

All above answer is correct but in my case There is no lib folder available in my app directory and I am trying to call below line in app gradle file

 compile fileTree(include: ['*.jar'], dir: 'libs')

So make sure what ever dependency you declare in gradle file in available for app

How to install OpenSSL for Python

SSL development libraries have to be installed

CentOS:

$ yum install openssl-devel libffi-devel

Ubuntu:

$ apt-get install libssl-dev libffi-dev

OS X (with Homebrew installed):

$ brew install openssl

React Native android build failed. SDK location not found

echo "sdk.dir = /Users/$(whoami)/Library/Android/sdk" > android/local.properties

How to extract text from a PDF?

On my Macintosh systems, I find that "Adobe Reader" does a reasonably good job. I created an alias on my Desktop that points to the "Adobe Reader.app", and all I do is drop a pdf-file on the alias, which makes it the active document in Adobe Reader, and then from the File-menu, I choose "Save as Text...", give it a name and where to save it, click "Save", and I'm done.

What is the size of column of int(11) in mysql in bytes?

4294967295 is the answer, because int(11) shows maximum of 11 digits IMO

PHP 5 disable strict standards error

All above solutions are correct. But, when we are talking about a normal PHP application, they have to included in every page, that it requires. A way to solve this, is through .htaccess at root folder. Just to hide the errors. [Put one of the followling lines in the file]

php_flag display_errors off

Or

php_value display_errors 0

Next, to set the error reporting

php_value error_reporting 30719

If you are wondering how the value 30719 came, E_ALL (32767), E_STRICT (2048) are actually constant that hold numeric value and (32767 - 2048 = 30719)

Convert char to int in C and C++

C and C++ always promote types to at least int. Furthermore character literals are of type int in C and char in C++.

You can convert a char type simply by assigning to an int.

char c = 'a'; // narrowing on C
int a = c;

Counting the number of files in a directory using Java

In spring batch I did below

private int getFilesCount() throws IOException {
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        Resource[] resources = resolver.getResources("file:" + projectFilesFolder + "/**/input/splitFolder/*.csv");
        return resources.length;
    }

How to make my font bold using css?

You'd use font-weight: bold.

Do you want to make the entire document bold? Or just parts of it?

How can I call a WordPress shortcode within a template?

Try this:

<?php 
/*
Template Name: [contact us]

*/
get_header();
echo do_shortcode('[CONTACT-US-FORM]'); 
?>

How to check if X server is running?

1)

# netstat -lp|grep -i x
tcp        0      0 *:x11                   *:*                     LISTEN      2937/X          
tcp6       0      0 [::]:x11                [::]:*                  LISTEN      2937/X          
Active UNIX domain sockets (only servers)
unix  2      [ ACC ]     STREAM     LISTENING     8940     2937/X              @/tmp/.X11-unix/X0
unix  2      [ ACC ]     STREAM     LISTENING     8941     2937/X              /tmp/.X11-unix/X0
#

2) nmap

# nmap localhost|grep -i x
6000/tcp open  X11
#

How to paginate with Mongoose in Node.js?

This is what I done it on code

var paginate = 20;
var page = pageNumber;
MySchema.find({}).sort('mykey', 1).skip((pageNumber-1)*paginate).limit(paginate)
    .exec(function(err, result) {
        // Write some stuff here
    });

That is how I done it.

Increase Tomcat memory settings

try setting this

CATALINA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 
-server -Xms1536m -Xmx1536m
-XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m 
-XX:MaxPermSize=256m -XX:+DisableExplicitGC"

in {$tomcat-folder}\bin\setenv.sh (create it if necessary).

See http://www.mkyong.com/tomcat/tomcat-javalangoutofmemoryerror-permgen-space/ for more details.

How to return a list of keys from a Hash Map?

map.keySet()

will return you all the keys. If you want the keys to be sorted, you might consider a TreeMap

How can I get the current time in C#?

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

Query to check index on a table

On Oracle:

  • Determine all indexes on table:

    SELECT index_name 
     FROM user_indexes
     WHERE table_name = :table
    
  • Determine columns indexes and columns on index:

    SELECT index_name
         , column_position
         , column_name
      FROM user_ind_columns
     WHERE table_name = :table
     ORDER BY index_name, column_order
    

References:

How to declare an array of strings in C++?

Instead of that macro, might I suggest this one:

template<typename T, int N>
inline size_t array_size(T(&)[N])
{
    return N;
}

#define ARRAY_SIZE(X)   (sizeof(array_size(X)) ? (sizeof(X) / sizeof((X)[0])) : -1)

1) We want to use a macro to make it a compile-time constant; the function call's result is not a compile-time constant.

2) However, we don't want to use a macro because the macro could be accidentally used on a pointer. The function can only be used on compile-time arrays.

So, we use the defined-ness of the function to make the macro "safe"; if the function exists (i.e. it has non-zero size) then we use the macro as above. If the function does not exist we return a bad value.

Which header file do you include to use bool type in c in linux?

Try this header file in your code

stdbool.h

This must work

How do I format a String in an email so Outlook will print the line breaks?

Not sure if it was mentioned above but Outlook has a checkbox setting called "Remove extra line breaks in plain text messages" and is checked by default. It is located in a different spot for different versions of Outlook but for 2010 go to the "File" tab. Select "Options => Mail" Scroll down to "Message format" Uncheck the checkbox.

Convert from days to milliseconds

Its important to mention that once in 4-5 years this method might give a 1 second error, becase of a leap-second (http://www.nist.gov/pml/div688/leapseconds.cfm), and the correct formula for that day would be

(24*60*60 + 1) * 1000

There is a question Are leap seconds catered for by Calendar? and the answer is no.

So, if You're designing super time-dependant software, be careful about this formula.

How to convert ActiveRecord results into an array of hashes

For current ActiveRecord (4.2.4+) there is a method to_hash on the Result object that returns an array of hashes. You can then map over it and convert to symbolized hashes:

# Get an array of hashes representing the result (column => value):
result.to_hash
# => [{"id" => 1, "title" => "title_1", "body" => "body_1"},
      {"id" => 2, "title" => "title_2", "body" => "body_2"},
      ...
     ]

result.to_hash.map(&:symbolize_keys)
# => [{:id => 1, :title => "title_1", :body => "body_1"},
      {:id => 2, :title => "title_2", :body => "body_2"},
      ...
     ]

See the ActiveRecord::Result docs for more info.

How do I execute a command and get the output of the command within C++ using POSIX?

I'd use popen() (++waqas).

But sometimes you need reading and writing...

It seems like nobody does things the hard way any more.

(Assuming a Unix/Linux/Mac environment, or perhaps Windows with a POSIX compatibility layer...)

enum PIPE_FILE_DESCRIPTERS
{
  READ_FD  = 0,
  WRITE_FD = 1
};

enum CONSTANTS
{
  BUFFER_SIZE = 100
};

int
main()
{
  int       parentToChild[2];
  int       childToParent[2];
  pid_t     pid;
  string    dataReadFromChild;
  char      buffer[BUFFER_SIZE + 1];
  ssize_t   readResult;
  int       status;

  ASSERT_IS(0, pipe(parentToChild));
  ASSERT_IS(0, pipe(childToParent));

  switch (pid = fork())
  {
    case -1:
      FAIL("Fork failed");
      exit(-1);

    case 0: /* Child */
      ASSERT_NOT(-1, dup2(parentToChild[READ_FD], STDIN_FILENO));
      ASSERT_NOT(-1, dup2(childToParent[WRITE_FD], STDOUT_FILENO));
      ASSERT_NOT(-1, dup2(childToParent[WRITE_FD], STDERR_FILENO));
      ASSERT_IS(0, close(parentToChild [WRITE_FD]));
      ASSERT_IS(0, close(childToParent [READ_FD]));

      /*     file, arg0, arg1,  arg2 */
      execlp("ls", "ls", "-al", "--color");

      FAIL("This line should never be reached!!!");
      exit(-1);

    default: /* Parent */
      cout << "Child " << pid << " process running..." << endl;

      ASSERT_IS(0, close(parentToChild [READ_FD]));
      ASSERT_IS(0, close(childToParent [WRITE_FD]));

      while (true)
      {
        switch (readResult = read(childToParent[READ_FD],
                                  buffer, BUFFER_SIZE))
        {
          case 0: /* End-of-File, or non-blocking read. */
            cout << "End of file reached..."         << endl
                 << "Data received was ("
                 << dataReadFromChild.size() << "): " << endl
                 << dataReadFromChild                << endl;

            ASSERT_IS(pid, waitpid(pid, & status, 0));

            cout << endl
                 << "Child exit staus is:  " << WEXITSTATUS(status) << endl
                 << endl;

            exit(0);


          case -1:
            if ((errno == EINTR) || (errno == EAGAIN))
            {
              errno = 0;
              break;
            }
            else
            {
              FAIL("read() failed");
              exit(-1);
            }

          default:
            dataReadFromChild . append(buffer, readResult);
            break;
        }
      } /* while (true) */
  } /* switch (pid = fork())*/
}

You also might want to play around with select() and non-blocking reads.

fd_set          readfds;
struct timeval  timeout;

timeout.tv_sec  = 0;    /* Seconds */
timeout.tv_usec = 1000; /* Microseconds */

FD_ZERO(&readfds);
FD_SET(childToParent[READ_FD], &readfds);

switch (select (1 + childToParent[READ_FD], &readfds, (fd_set*)NULL, (fd_set*)NULL, & timeout))
{
  case 0: /* Timeout expired */
    break;

  case -1:
    if ((errno == EINTR) || (errno == EAGAIN))
    {
      errno = 0;
      break;
    }
    else
    {
      FAIL("Select() Failed");
      exit(-1);
    }

  case 1:  /* We have input */
    readResult = read(childToParent[READ_FD], buffer, BUFFER_SIZE);
    // However you want to handle it...
    break;

  default:
    FAIL("How did we see input on more than one file descriptor?");
    exit(-1);
}

Alternate background colors for list items

Try adding a pair of class attributes, say 'even' and 'odd', to alternating list elements, e.g.

<ul>
    <li class="even"><a href="link">Link 1</a></li>
    <li class="odd"><a href="link">Link 2</a></li>
    <li class="even"><a href="link">Link 3</a></li>
    <li class="odd"><a href="link">Link 4</a></li>
    <li class="even"><a href="link">Link 5</a></li>
</ul>

In a <style> section of the HTML page, or in a linked stylesheet, you would define those same classes, specifying your desired background colours:

li.even { background-color: red; }
li.odd { background-color: blue; }

You might want to use a template library as your needs evolve to provide you with greater flexibility and to cut down on the typing. Why type all those list elements by hand?

Where does linux store my syslog?

On my Ubuntu machine, I can see the output at /var/log/syslog.

On a RHEL/CentOS machine, the output is found in /var/log/messages.

This is controlled by the rsyslog service, so if this is disabled for some reason you may need to start it with systemctl start rsyslog.

As noted by others, your syslog() output would be logged by the /var/log/syslog file.
You can see system, user, and other logs at /var/log.

For more details: here's an interesting link.

Get the closest number out of an array

Another variant here we have circular range connecting head to toe and accepts only min value to given input. This had helped me get char code values for one of the encryption algorithm.

function closestNumberInCircularRange(codes, charCode) {
  return codes.reduce((p_code, c_code)=>{
    if(((Math.abs(p_code-charCode) > Math.abs(c_code-charCode)) || p_code > charCode) && c_code < charCode){
      return c_code;
    }else if(p_code < charCode){
      return p_code;
    }else if(p_code > charCode && c_code > charCode){
      return Math.max.apply(Math, [p_code, c_code]);
    }
    return p_code;
  });
}

How to tag docker image with docker-compose

you can try:

services:
  nameis:
    container_name: hi_my
    build: .
    image: hi_my_nameis:v1.0.0

Replace all 0 values to NA

dplyr::na_if() is an option:

library(dplyr)  

df <- data_frame(col1 = c(1, 2, 3, 0),
                 col2 = c(0, 2, 3, 4),
                 col3 = c(1, 0, 3, 0),
                 col4 = c('a', 'b', 'c', 'd'))

na_if(df, 0)
# A tibble: 4 x 4
   col1  col2  col3 col4 
  <dbl> <dbl> <dbl> <chr>
1     1    NA     1 a    
2     2     2    NA b    
3     3     3     3 c    
4    NA     4    NA d

Better way of getting time in milliseconds in javascript?

If you have date object like

var date = new Date('2017/12/03');

then there is inbuilt method in javascript for getting date in milliseconds format which is valueOf()

date.valueOf(); //1512239400000 in milliseconds format

New lines (\r\n) are not working in email body

You can add new line character in text/plain content type using %0A character code.

For example:

<a href="mailto:[email protected]?subject=Hello%20again&body=HI%20%0AThis%20is%20a%20new%20line"/>

Here is the jsfiddle

Real mouse position in canvas

Refer this question: The mouseEvent.offsetX I am getting is much larger than actual canvas size .I have given a function there which will exactly suit in your situation

Why does Python code use len() function instead of a length method?

Python is a pragmatic programming language, and the reasons for len() being a function and not a method of str, list, dict etc. are pragmatic.

The len() built-in function deals directly with built-in types: the CPython implementation of len() actually returns the value of the ob_size field in the PyVarObject C struct that represents any variable-sized built-in object in memory. This is much faster than calling a method -- no attribute lookup needs to happen. Getting the number of items in a collection is a common operation and must work efficiently for such basic and diverse types as str, list, array.array etc.

However, to promote consistency, when applying len(o) to a user-defined type, Python calls o.__len__() as a fallback. __len__, __abs__ and all the other special methods documented in the Python Data Model make it easy to create objects that behave like the built-ins, enabling the expressive and highly consistent APIs we call "Pythonic".

By implementing special methods your objects can support iteration, overload infix operators, manage contexts in with blocks etc. You can think of the Data Model as a way of using the Python language itself as a framework where the objects you create can be integrated seamlessly.

A second reason, supported by quotes from Guido van Rossum like this one, is that it is easier to read and write len(s) than s.len().

The notation len(s) is consistent with unary operators with prefix notation, like abs(n). len() is used way more often than abs(), and it deserves to be as easy to write.

There may also be a historical reason: in the ABC language which preceded Python (and was very influential in its design), there was a unary operator written as #s which meant len(s).

How do I make a WPF TextBlock show my text on multiple lines?

Use the property TextWrapping of the TextBlock element:

<TextBlock Text="StackOverflow Forum"
           Width="100"
           TextWrapping="WrapWithOverflow"/>

How to get all the values of input array element jquery

Use:

function getvalues(){
var inps = document.getElementsByName('pname[]');
for (var i = 0; i <inps.length; i++) {
var inp=inps[i];
    alert("pname["+i+"].value="+inp.value);
}
}

Here is Demo.

How should I cast in VB.NET?

At one time, I remember seeing the MSDN library state to use CStr() because it was faster. I do not know if this is true though.

Google Maps Android API v2 - Interactive InfoWindow (like in original android google maps)

I have build a sample android studio project for this question.

output screen shots :-

enter image description here

enter image description here

enter image description here

Download full project source code Click here

Please note: you have to add your API key in Androidmanifest.xml

How to fix Uncaught InvalidValueError: setPosition: not a LatLng or LatLngLiteral: in property lat: not a number?

You're probably passing null value if you're loading the coordinates dynamically, set a check before you call the map loader ie: if(mapCords){loadMap}

Git command to checkout any branch and overwrite local changes

git reset and git clean can be overkill in some situations (and be a huge waste of time).

If you simply have a message like "The following untracked files would be overwritten..." and you want the remote/origin/upstream to overwrite those conflicting untracked files, then git checkout -f <branch> is the best option.

If you're like me, your other option was to clean and perform a --hard reset then recompile your project.

How to paste into a terminal?

On windows 7:

Ctrl + Shift + Ins

works for me!

Why functional languages?

My view is that it will catch on now that Microsoft have pushed it much further into the mainstream. For me it's attractive because of what it can do for us, because it's a new challenge and because of the job opportunities it resents for the future.

Once mastered it will be another tool to further help make us more productive as programmers.

Set database timeout in Entity Framework

My partial context looks like:

public partial class MyContext : DbContext
{
    public MyContext (string ConnectionString)
        : base(ConnectionString)
    {
        this.SetCommandTimeOut(300);
    }

    public void SetCommandTimeOut(int Timeout)
    {
        var objectContext = (this as IObjectContextAdapter).ObjectContext;
        objectContext.CommandTimeout = Timeout;
    }
}

I left SetCommandTimeOut public so only the routines I need to take a long time (more than 5 minutes) I modify instead of a global timeout.

PHP Accessing Parent Class Variable

With parent::$bb; you try to retrieve the static constant defined with the value of $bb.

Instead, do:

echo $this->bb;

Note: you don't need to call parent::_construct if B is the only class that calls it. Simply don't declare __construct in B class.

Connect multiple devices to one device via Bluetooth

Yes, that is possible. At its lowest level Bluetooth allows you to connect up to 7 devices to one master device. I have done this and it has worked well for me, but only on other platforms (linux) where I had lots of manual control - I've never tried that on Android and there are some possible complications so you will need to do some testing to be certain.

One of the issues is that you need the tablet to the master and Android doesn't give you any explicit control of this. It is likely that this won't be a problem because * the tablet will automatically become the master when you try to connect a second device to it, or * you will be able to control the master/slave roles by how you setup your socket connection

I will caution though that most apps using Bluetooth on mobile are not attempting many simultaneous connections and Bluetooth can be a bit fragile, e.g. what if two devices already have a Bluetooth connection for some other app - how might that affect the roles?

Images can't contain alpha channels or transparencies

Photoshop

  1. Slice it
  2. Save for web
  3. Uncheck Transparency

Error "library not found for" after putting application in AdMob

If error related to Cocoapods as follow:

library not found for -lPod-...

You need to check Other Linker Flags and remove it from there.

Extra Information: If you have an old project that uses cocoapods. And recently you needed to add the use_frameworks! to your podfile. cocoapods will not add the libraries to your Other Linker Flags anymore cause its inherited. Therefore, you may need to remove those manually from the other linker flags which they were added before using the use_frameworks!

How to check whether an object has certain method/property?

via Reflection

 var property = object.GetType().GetProperty("YourProperty")
 property.SetValue(object,some_value,null);

Similar is for methods

Apply function to all elements of collection through LINQ

You can try something like

var foo = (from fooItems in context.footable select fooItems.fooID + 1);

Returns a list of id's +1, you can do the same with using a function to whatever you have in the select clause.

Update: As suggested from Jon Skeet this is a better version of the snippet of code I just posted:

var foo = context.footable.Select(foo => foo.fooID + 1);

How can I format a String number to have commas and round?

public void convert(int s)
{
    System.out.println(NumberFormat.getNumberInstance(Locale.US).format(s));
}

public static void main(String args[])
{
    LocalEx n=new LocalEx();
    n.convert(10000);
}

Unexpected token ILLEGAL in webkit

This error can also be caused by a javascript line like this one:

navi_elements.style.bottom = 20px;

Notice that the value is not a string.

In Spring MVC, how can I set the mime type header when using @ResponseBody

I would consider to refactor the service to return your domain object rather than JSON strings and let Spring handle the serialization (via the MappingJacksonHttpMessageConverter as you write). As of Spring 3.1, the implementation looks quite neat:

@RequestMapping(produces = MediaType.APPLICATION_JSON_VALUE, 
    method = RequestMethod.GET
    value = "/foo/bar")
@ResponseBody
public Bar fooBar(){
    return myService.getBar();
}

Comments:

First, the <mvc:annotation-driven /> or the @EnableWebMvc must be added to your application config.

Next, the produces attribute of the @RequestMapping annotation is used to specify the content type of the response. Consequently, it should be set to MediaType.APPLICATION_JSON_VALUE (or "application/json").

Lastly, Jackson must be added so that any serialization and de-serialization between Java and JSON will be handled automatically by Spring (the Jackson dependency is detected by Spring and the MappingJacksonHttpMessageConverter will be under the hood).

RE error: illegal byte sequence on Mac OS X

Does anyone know how to get sed to print the position of the illegal byte sequence? Or does anyone know what the illegal byte sequence is?

$ uname -a
Darwin Adams-iMac 18.7.0 Darwin Kernel Version 18.7.0: Tue Aug 20 16:57:14 PDT 2019; root:xnu-4903.271.2~2/RELEASE_X86_64 x86_64

I got part of the way to answering the above just by using tr.

I have a .csv file that is a credit card statement and I am trying to import it into Gnucash. I am based in Switzerland so I have to deal with words like Zürich. Suspecting Gnucash does not like " " in numeric fields, I decide to simply replace all

; ;

with

;;

Here goes:

$ head -3 Auswertungen.csv | tail -1 | sed -e 's/; ;/;;/g'
sed: RE error: illegal byte sequence

I used od to shed some light: Note the 374 halfway down this od -c output

$ head -3 Auswertungen.csv | tail -1 | od -c
0000000    1   6   8   7       9   6   1   9       7   1   2   2   ;   5
0000020    4   6   8       8   7   X   X       X   X   X   X       2   6
0000040    6   0   ;   M   Y       N   A   M   E       I   S   X   ;   1
0000060    4   .   0   2   .   2   0   1   9   ;   9   5   5   2       -
0000100        M   i   t   a   r   b   e   i   t   e   r   r   e   s   t
0000120                Z 374   r   i   c   h                            
0000140    C   H   E   ;   R   e   s   t   a   u   r   a   n   t   s   ,
0000160        B   a   r   s   ;   6   .   2   0   ;   C   H   F   ;    
0000200    ;   C   H   F   ;   6   .   2   0   ;       ;   1   5   .   0
0000220    2   .   2   0   1   9  \n                                    
0000227

Then I thought I might try to persuade tr to substitute 374 for whatever the correct byte code is. So first I tried something simple, which didn't work, but had the side effect of showing me where the troublesome byte was:

$ head -3 Auswertungen.csv | tail -1 | tr . .  ; echo
tr: Illegal byte sequence
1687 9619 7122;5468 87XX XXXX 2660;MY NAME ISX;14.02.2019;9552 - Mitarbeiterrest   Z

You can see tr bails at the 374 character.

Using perl seems to avoid this problem

$ head -3 Auswertungen.csv | tail -1 | perl -pne 's/; ;/;;/g'
1687 9619 7122;5468 87XX XXXX 2660;ADAM NEALIS;14.02.2019;9552 - Mitarbeiterrest   Z?rich       CHE;Restaurants, Bars;6.20;CHF;;CHF;6.20;;15.02.2019

LaTeX "\indent" creating paragraph indentation / tabbing package requirement?

This is kind of a hack but the best solution that I have found is to use a description tag with no \item. This will produce an error from the latex compiler; however, the error does not prevent the pdf from being generated.

\begin{description} 
     <YOUR TEXT HERE> 
\end{description}
  • This only worked on windows latex compiler

How to detect input type=file "change" for the same file?

The simplest way would be to set the input value to an empty string directly in the change or input event, which one mostly listens to anyways.

onFileInputChanged(event) {
     // todo: read the filenames and do the work
     
     // reset the value directly using the srcElement property from the event
     event.srcElement.value = ""
}

Split function equivalent in T-SQL?

You've tagged this SQL Server 2008 but future visitors to this question (using SQL Server 2016+) will likely want to know about STRING_SPLIT.

With this new builtin function you can now just use

SELECT TRY_CAST(value AS INT)
FROM   STRING_SPLIT ('1,2,3,4,5,6,7,8,9,10,11,12,13,14,15', ',') 

Some restrictions of this function and some promising results of performance testing are in this blog post by Aaron Bertrand.

Unsupported major.minor version 52.0 in my app

This problem stems from the fact that your build tool version and JDK won't work together. I was using JDK version 7 with build tool 24.0.1. Of course lowering build tool version may fix the problem but it is not a real fix, as upgrading your build tools in future will break it again.

You should make sure build tool version and JDK work together. I upgraded my build tool to latest (24.0.1) and installed jdk8. Make sure to set your JAVA_HOME to latest and then try clean build.

How to call a web service from jQuery

Incase people have a problem like myself following Marwan Aouida's answer ... the code has a small typo. Instead of "success" it says "sucess" change the spelling and the code works fine.

Error: "Adb connection Error:An existing connection was forcibly closed by the remote host"

In my case, which none of the answers above stated. If your device is using the miniUsb connector, make sure you are using a cable that is not charge-only. I became accustom to using developing with a newer Usb-C device and could not fathom a charge-only cable got mixed with my pack especially since there is no visible way to tell the difference.

Before you uninstall and go through a nightmare of driver reinstall and android menu options. Try a different cable first.

How to delete a certain row from mysql table with same column values?

There are already answers for Deleting row by LIMIT. Ideally you should have primary key in your table. But if there is not.

I will give other ways:

  1. By creating Unique index

I see id_users and id_product should be unique in your example.

ALTER IGNORE TABLE orders ADD UNIQUE INDEX unique_columns_index (id_users, id_product)

These will delete duplicate rows with same data.

But if you still get an error, even if you use IGNORE clause, try this:

ALTER TABLE orders ENGINE MyISAM;
ALTER IGNORE TABLE orders ADD UNIQUE INDEX unique_columns_index (id_users, id_product)
ALTER TABLE orders ENGINE InnoDB; 
  1. By creating table again

If there are multiple rows who have duplicate values, then you can also recreate table

RENAME TABLE `orders` TO `orders2`;

CREATE TABLE `orders` 
SELECT * FROM `orders2` GROUP BY id_users, id_product;

Check OS version in Swift?

Update for Swift 3.0+

func SYSTEM_VERSION_EQUAL_TO(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: .numeric) == ComparisonResult.orderedSame
}

func SYSTEM_VERSION_GREATER_THAN(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: .numeric) == ComparisonResult.orderedDescending
}

func SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: .numeric) != ComparisonResult.orderedAscending
}

func SYSTEM_VERSION_LESS_THAN(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: .numeric) == ComparisonResult.orderedAscending
}

func SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(version: String) -> Bool {
    return UIDevice.current.systemVersion.compare(version, options: .numeric) != ComparisonResult.orderedDescending
}

How to change button background image on mouseOver?

You can create a class based on a Button with specific images for MouseHover and MouseDown like this:

public class AdvancedImageButton : Button {

public Image HoverImage { get; set; }
public Image PlainImage { get; set; }
public Image PressedImage { get; set; }

protected override void OnMouseEnter(System.EventArgs e)
{
  base.OnMouseEnter(e);
  if (HoverImage == null) return;
  if (PlainImage == null) PlainImage = base.Image;
  base.Image = HoverImage;
}

protected override void OnMouseLeave(System.EventArgs e)
{
  base.OnMouseLeave(e);
  if (HoverImage == null) return;
  base.Image = PlainImage;
}

protected override void OnMouseDown(MouseEventArgs e)
{
  base.OnMouseDown(e);
  if (PressedImage == null) return;
  if (PlainImage == null) PlainImage = base.Image;
  base.Image = PressedImage;
}

}

This solution has a small drawback that I am sure can be fixed: when you need for some reason change the Image property, you will also have to change the PlainImage property also.

FileNotFoundException..Classpath resource not found in spring?

Two things worth pointing out:

  1. The scope of your spring-context dependency shouldn't be "runtime", but "compile", which is the default, so you can just remove the scope line.
  2. You should configure the compiler plugin to compile to at least java 1.5 to handle the annotations when building with Maven. (Can also affect IDE settings, though Eclipse doesn't tend to care.)

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.5</source>
                    <target>1.5</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    

After that, reconfiguring your project from Maven should fix it. I don't recall exactly how to do that in Eclipse, but you should find it if you right click the project node and poke around the menus.

how to add a jpg image in Latex

if you add a jpg,png,pdf picture, you should use pdflatex to compile it.

Android dex gives a BufferOverflowException when building

None of the other solutions here worked for me after upgrading to Android Studio 0.4.0 and Gradle 1.9.

I resolved the problem by downloading Build Tools 19.0.1 and updating the following line in my build.gradle files:

buildToolsVersion '19.0.0'

to

buildToolsVersion '19.0.1'

How can I present a file for download from an MVC controller?

Use .ashx file type and use the same code

Java SE 6 vs. JRE 1.6 vs. JDK 1.6 - What do these mean?

With the release of Java 5, the product version was made distinct from the developer version as described here

Use Font Awesome icon as CSS content

Another solution without you having to manually mess around with the Unicode characters can be found in Making Font Awesome awesome - Using icons without i-tags (disclaimer: I wrote this article).

In a nutshell, you can create a new class like this:

.icon::before {
    display: inline-block;
    margin-right: .5em;
    font: normal normal normal 14px/1 FontAwesome;
    font-size: inherit;
    text-rendering: auto;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transform: translate(0, 0);
}

And then use it with any icon, for example:

<a class="icon fa-car" href="#">This is a link</a>

How do I read a file line by line in VB Script?

If anyone like me is searching to read only a specific line, example only line 18 here is the code:

filename = "C:\log.log"

Set fso = CreateObject("Scripting.FileSystemObject")
Set f = fso.OpenTextFile(filename)

For i = 1 to 17
    f.ReadLine
Next

strLine = f.ReadLine
Wscript.Echo strLine

f.Close

SPA best practices for authentication and session management

I would go for the second, the token system.

Did you know about ember-auth or ember-simple-auth? They both use the token based system, like ember-simple-auth states:

A lightweight and unobtrusive library for implementing token based authentication in Ember.js applications. http://ember-simple-auth.simplabs.com

They have session management, and are easy to plug into existing projects too.

There is also an Ember App Kit example version of ember-simple-auth: Working example of ember-app-kit using ember-simple-auth for OAuth2 authentication.

iOS9 Untrusted Enterprise Developer with no option to trust

Do it like this:

Enter image description here

Go to Settings -> General -> Profiles - tap on your Profile - tap on the Trust button.

but iOS10 has a little change,

Users should go to Settings - General - Device Management - tap on your Profile - tap on Trust button.

enter image description here

Reference: iOS10AdaptationTips

How to convert all tables from MyISAM into InnoDB?

<?php

// Convert all MyISAM tables to INNODB tables in all non-special databases.
// Note: With MySQL less than 5.6, tables with a fulltext search index cannot be converted to INNODB and will be skipped.

if($argc < 4)
    exit("Usage: {$argv[0]} <host> <username> <password>\n");
$host = $argv[1];
$username = $argv[2];
$password = $argv[3];

// Connect to the database.
if(!mysql_connect($host, $username, $password))
    exit("Error opening database. " . mysql_error() . "\n");

// Get all databases except special ones that shouldn't be converted.
$databases = mysql_query("SHOW databases WHERE `Database` NOT IN ('mysql', 'information_schema', 'performance_schema')");
if($databases === false)
    exit("Error showing databases. " . mysql_error() . "\n");

while($db = mysql_fetch_array($databases))
{
    // Select the database.
    if(!mysql_select_db($db[0]))
        exit("Error selecting database: {$db[0]}. " . mysql_error() . "\n");
    printf("Database: %s\n", $db[0]);

    // Get all MyISAM tables in the database.
    $tables = mysql_query("SHOW table status WHERE Engine = 'MyISAM'");
    if($tables === false)
        exit("Error showing tables. " . mysql_error() . "\n");

    while($tbl = mysql_fetch_array($tables))
    {
        // Convert the table to INNODB.
        printf("--- Converting %s\n", $tbl[0]);
        if(mysql_query("ALTER TABLE `{$tbl[0]}` ENGINE = INNODB") === false)
            printf("--- --- Error altering table: {$tbl[0]}. " . mysql_error() . "\n");
    }
}

mysql_close();

?>

PHP multidimensional array search by value

If you are using (PHP 5 >= 5.5.0) you don't have to write your own function to do this, just write this line and it's done.

If you want just one result:

$key = array_search(40489, array_column($userdb, 'uid'));

For multiple results

$keys = array_keys(array_column($userdb, 'uid'), 40489);

In case you have an associative array as pointed in the comments you could make it with:

$keys = array_keys(array_combine(array_keys($userdb), array_column($userdb, 'uid')),40489);

If you are using PHP < 5.5.0, you can use this backport, thanks ramsey!

Update: I've been making some simple benchmarks and the multiple results form seems to be the fastest one, even faster than the Jakub custom function!

Razor View throwing "The name 'model' does not exist in the current context"

There appear to be 3 version-number settings which need to be correct in relation to each other here:

  1. ... System.Web.Mvc, Version=x.x.x.x ... (in various places ~\Views\web.config)
  2. ... System.Web.WebPages.Razor, Version=x.x.x.x ... (in various places ~\Views\web.config)
  3. <add key="webpages:Version" value="x.x.x.x" /> (in ~\web.config) NB: root web.config

Combinations that have worked for me:

Combination 1:

System.Web.Mvc, Version=4.0.0.0

System.Web.WebPages.Razor, Version=2.0.0.0

<add key="webpages:Version" value="2.0.0.0" />

Combination 2:

System.Web.Mvc, Version=5.2.7.0

System.Web.WebPages.Razor, Version=3.0.0.0

<add key="webpages:Version" value="3.0.0.0" />

A final observation is that the webpages:Version setting appears to be optional. Removing it appears to have no negative consequences, at least in the context of the issue at hand.

Parse HTML table to Python list?

If the HTML is not XML you can't do it with etree. But even then, you don't have to use an external library for parsing a HTML table. In python 3 you can reach your goal with HTMLParser from html.parser. I've the code of the simple derived HTMLParser class here in a github repo.

You can use that class (here named HTMLTableParser) the following way:

import urllib.request
from html_table_parser import HTMLTableParser

target = 'http://www.twitter.com'

# get website content
req = urllib.request.Request(url=target)
f = urllib.request.urlopen(req)
xhtml = f.read().decode('utf-8')

# instantiate the parser and feed it
p = HTMLTableParser()
p.feed(xhtml)
print(p.tables)

The output of this is a list of 2D-lists representing tables. It looks maybe like this:

[[['   ', ' Anmelden ']],
 [['Land', 'Code', 'Für Kunden von'],
  ['Vereinigte Staaten', '40404', '(beliebig)'],
  ['Kanada', '21212', '(beliebig)'],
  ...
  ['3424486444', 'Vodafone'],
  ['  Zeige SMS-Kurzwahlen für andere Länder ']]]

How to crop an image using PIL?

There is a crop() method:

w, h = yourImage.size
yourImage.crop((0, 30, w, h-30)).save(...)

How to know the git username and email saved during configuration?

If you want to check or set the user name and email you can use the below command

Check user name

git config user.name

Set user name

git config user.name "your_name"

Check your email

git config user.email

Set/change your email

git config user.email "[email protected]"

List/see all configuration

git config --list

Which JRE am I using?

  1. Open up your:
    • command prompt if you're using Windows
    • terminal if you're using mac or Linux
  2. Type in:

    java -version // This will check your JRE version
    javac -version // This will check your Java compiler version if you installed the JDK
    
  3. Grab a cup of coffee and you're done! You don't need to add the .exe to the java -version if everything is installed correctly.

What is the point of WORKDIR on Dockerfile?

Be careful where you set WORKDIR because it can affect the continuous integration flow. For example, setting it to /home/circleci/project will cause error something like .ssh or whatever is the remote circleci is doing at setup time.

gpg decryption fails with no secret key error

I have solved this problem, try to use root privileges, such as sudo gpg ... I think that gpg elevated without permissions does not refer to file permissions, but system

How can I center text (horizontally and vertically) inside a div block?

Apply style:

position: absolute;
top: 50%;
left: 0;
right: 0;

Your text would be centered irrespective of its length.

Update Top 1 record in table sql server

WITH UpdateList_view AS (
  SELECT TOP 1  * from TX_Master_PCBA 
  WHERE SERIAL_NO IN ('0500030309') 
  ORDER BY TIMESTAMP2 DESC 
)

update UpdateList_view 
set TIMESTAMP2 = '2013-12-12 15:40:31.593'

How do I convert a Python program to a runnable .exe Windows program?

Understand that every 'freezing' application for Python will not really secure your code in any way. Every packaging system for a stand-alone executable Python 'program' will include a lot of the Python libraries and interpreter, which will make your program pretty large.

That said, PyInstaller has done a nearly flawless job with everything I've thrown at it. Currently it only supports up to Python 2.7 but Pyinstaller's support for a varied set of libraries large and small is unmatched in other 'freeze' type programs for Python.

How to remove a package from Laravel using composer?

We have come with a great solution. This solution is practically done in Laravel 6. If you want to remove any package from your Laravel Project then you can easily remove the package by following below steps:

Step 1: You must know the package name which you want to remove. If you don't know complete package name then you can open your project folder and go to composer.json file and check name in require an array

"require": {
        "php": "^7.2",
        "fideloper/proxy": "^4.0",
        "laravel/framework": "^6.2",
        "laravel/passport": "^8.3",
        "laravel/tinker": "^2.0"
    },

Suppose, here I am going to remove "fideloper/proxy" package.

Step 2: Open command prompt with your project root folder directory enter image description here Step 3: First of all clear all cache by following commands. Run commands one by one.

php artisan cache:clear  
php artisan config:clear 

Step 4: Now write the following command to remove the package. Here you need to change your package name instead of my example package.

composer remove fideloper/proxy

Now, wait for a few seconds your package is removing.

How to get `DOM Element` in Angular 2?

Use ViewChild with #localvariable as shown here,

<textarea  #someVar  id="tasknote"
                  name="tasknote"
                  [(ngModel)]="taskNote"
                  placeholder="{{ notePlaceholder }}"
                  style="background-color: pink"
                  (blur)="updateNote() ; noteEditMode = false " (click)="noteEditMode = false"> {{ todo.note }} 

</textarea>

In component,

OLDEST Way

import {ElementRef} from '@angular/core';
@ViewChild('someVar') el:ElementRef;

ngAfterViewInit()
{
   this.el.nativeElement.focus();
}


OLD Way

import {ElementRef} from '@angular/core';
@ViewChild('someVar') el:ElementRef;

constructor(private rd: Renderer) {}
ngAfterViewInit() {
    this.rd.invokeElementMethod(this.el.nativeElement,'focus');
}


Updated on 22/03(March)/2017

NEW Way

Please note from Angular v4.0.0-rc.3 (2017-03-10) few things have been changed. Since Angular team will deprecate invokeElementMethod, above code no longer can be used.

BREAKING CHANGES

since 4.0 rc.1:

rename RendererV2 to Renderer2
rename RendererTypeV2 to RendererType2
rename RendererFactoryV2 to RendererFactory2

import {ElementRef,Renderer2} from '@angular/core';
@ViewChild('someVar') el:ElementRef;

constructor(private rd: Renderer2) {}

ngAfterViewInit() {
      console.log(this.rd); 
      this.el.nativeElement.focus();      //<<<=====same as oldest way
}

console.log(this.rd) will give you following methods and you can see now invokeElementMethod is not there. Attaching img as yet it is not documented.

NOTE: You can use following methods of Rendere2 with/without ViewChild variable to do so many things.

enter image description here

convert a char* to std::string

char* data;
std::string myString(data);

how to prevent adding duplicate keys to a javascript array

function check (list){
    var foundRepeatingValue = false;
    var newList = [];
    for(i=0;i<list.length;i++){
        var thisValue = list[i];
        if(i>0){
            if(newList.indexOf(thisValue)>-1){
                foundRepeatingValue = true;
                console.log("getting repeated");
                return true;
            }
       } newList.push(thisValue);
    } return false;
}

 

var list1 = ["dse","dfg","dse"];
check(list1);

Output:

getting repeated
true

Is there an upside down caret character?

An upside-down circumflex is called a caron, or a hácek.

It has an HTML entity in the TADS Latin-2 extension to HTML: &caron; and looks like this: ˇ which unfortunately doesn't display in the same size/proportion as the ^ caret.

Or you can use the unicode U+30C.

TypeError: 'builtin_function_or_method' object is not subscriptable

Can't believe this thread was going on for so long. You would get this error if you got distracted and used [] instead of (), at least my case.

Pop is a method on the list data type, https://docs.python.org/2/tutorial/datastructures.html#more-on-lists

Therefore, you shouldn't be using pop as if it was a list itself, pop[0]. It's a method that takes an optional parameter representing an index, so as Tushar Palawat pointed out in one of the answers that didn't get approved, the correct adjustment which will fix the example above is:

listb.pop(0)

If you don't believe, run a sample such as:

if __name__ == '__main__':
  listb = ["-test"]
  if( listb[0] == "-test"):
    print(listb.pop(0))

Other adjustments would work as well, but it feels as they are abusing the Python language. This thread needs to get fixed, not to confuse users.

Addition, a.pop() removes and returns the last item in the list. As a result, a.pop()[0] will get the first character of that last element. It doesn't seem that is what the given code snippet is aiming to achieve.

Docker-Compose can't connect to Docker Daemon

I got this error when there were files in the Dockerfile directory that were not accessible by the current user. docker could thus not upload the full context to the daemon and brought the "Couldn't connect to Docker daemon at http+docker://localunixsocket" message.

Execute cmd command from VBScript

Can also invoke oShell.Exec in order to be able to read STDIN/STDOUT/STDERR responses. Perfect for error checking which it seems you're doing with your sanity .BAT.

Java 8 lambda Void argument

That is not possible. A function that has a non-void return type (even if it's Void) has to return a value. However you could add static methods to Action that allows you to "create" a Action:

interface Action<T, U> {
   U execute(T t);

   public static Action<Void, Void> create(Runnable r) {
       return (t) -> {r.run(); return null;};
   }

   public static <T, U> Action<T, U> create(Action<T, U> action) {
       return action;
   } 
}

That would allow you to write the following:

// create action from Runnable
Action.create(()-> System.out.println("Hello World")).execute(null);
// create normal action
System.out.println(Action.create((Integer i) -> "number: " + i).execute(100));

Input widths on Bootstrap 3

You don't have to give up simple css :)

.short { max-width: 300px; }
<input type="text" class="form-control short" id="...">

how to delete a specific row in codeigniter?

It will come in the url so you can get it by two ways. Fist one

<td><?php echo anchor('textarea/delete_row', 'DELETE', 'id="$row->id"'); ?></td>
$id = $this->input->get('id');

2nd one.

$id = $this->uri->segment(3);

But in the second method you have to count the no. of segments in the url that on which no. your id come. 2,3,4 etc. then you have to pass. then in the ();

Submitting a form by pressing enter without a submit button

the simplest way

<input type="submit" style="width:0px; height:0px; opacity:0;"/>

Add object to ArrayList at specified index

I draw your attention to the ArrayList.add documentation, which says it throws IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())

Check the size() of your list before you call list.add(1, object1)

How to handle calendar TimeZones using Java?

public static Calendar convertToGmt(Calendar cal) {

    Date date = cal.getTime();
    TimeZone tz = cal.getTimeZone();

    log.debug("input calendar has date [" + date + "]");

    //Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT 
    long msFromEpochGmt = date.getTime();

    //gives you the current offset in ms from GMT at the current date
    int offsetFromUTC = tz.getOffset(msFromEpochGmt);
    log.debug("offset is " + offsetFromUTC);

    //create a new calendar in GMT timezone, set to this date and add the offset
    Calendar gmtCal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
    gmtCal.setTime(date);
    gmtCal.add(Calendar.MILLISECOND, offsetFromUTC);

    log.debug("Created GMT cal with date [" + gmtCal.getTime() + "]");

    return gmtCal;
}

Here's the output if I pass the current time ("12:09:05 EDT" from Calendar.getInstance()) in:

DEBUG - input calendar has date [Thu Oct 23 12:09:05 EDT 2008]
DEBUG - offset is -14400000
DEBUG - Created GMT cal with date [Thu Oct 23 08:09:05 EDT 2008]

12:09:05 GMT is 8:09:05 EDT.

The confusing part here is that Calendar.getTime() returns you a Date in your current timezone, and also that there is no method to modify the timezone of a calendar and have the underlying date rolled also. Depending on what type of parameter your web service takes, your may just want to have the WS deal in terms of milliseconds from epoch.

IntelliJ IDEA "cannot resolve symbol" and "cannot resolve method"

First check if you have configured JDK correctly:

  • Go to File->Project Structure -> SDKs
  • your JDK home path should be something like this: /Library/Java/JavaVirtualMachine/jdk.1.7.0_79.jdk/Contents/Home
  • Hit Apply and then OK

Secondly check if you have provided in path in Library's section

  • Go to File->Project Structure -> Libraries
  • Hit the + button
  • Add the path to your src folder
  • Hit Apply and then OK

This should fix the problem

java.time.format.DateTimeParseException: Text could not be parsed at index 21

If your input always has a time zone of "zulu" ("Z" = UTC), then you can use DateTimeFormatter.ISO_INSTANT (implicitly):

final Instant parsed = Instant.parse(dateTime);

If time zone varies and has the form of "+01:00" or "+01:00:00" (when not "Z"), then you can use DateTimeFormatter.ISO_OFFSET_DATE_TIME:

DateTimeFormatter formatter = DateTimeFormatter.ISO_OFFSET_DATE_TIME;
final ZonedDateTime parsed = ZonedDateTime.parse(dateTime, formatter);

If neither is the case, you can construct a DateTimeFormatter in the same manner as DateTimeFormatter.ISO_OFFSET_DATE_TIME is constructed.


Your current pattern has several problems:

  • not using strict mode (ResolverStyle.STRICT);
  • using yyyy instead of uuuu (yyyy will not work in strict mode);
  • using 12-hour hh instead of 24-hour HH;
  • using only one digit S for fractional seconds, but input has three.

CSS3 Spin Animation

You haven't specified any keyframes. I made it work here.

div {
    margin: 20px;
    width: 100px; 
    height: 100px;    
    background: #f00;
    -webkit-animation: spin 4s infinite linear;
}

@-webkit-keyframes spin {
    0%  {-webkit-transform: rotate(0deg);}
    100% {-webkit-transform: rotate(360deg);}   
}

You can actually do lots of really cool stuff with this. Here is one I made earlier.

:)

N.B. You can skip having to write out all the prefixes if you use -prefix-free.

Remove scrollbar from iframe

Add scrolling="no" attribute to the iframe.

jQuery How do you get an image to fade in on load?

Simply set the logo's style to display:hidden and call fadeIn, instead of first calling hide:

$(document).ready(function() {
    $('#logo').fadeIn("normal");
});

<img src="logo.jpg" style="display:none"/>

.NET Core vs Mono

Necromancing.
Providing an actual answer.

What is the difference between .Net Core and Mono?

.NET Core now officially is the future of .NET. It started for most part with a re-write of the ASP.NET MVC framework and console applications, which of course includes server applications. (Since it's Turing-complete and supports interop with C dlls, you could, if you absolutely wanted to, also write your own desktop applications with it, for example through 3rd-party libraries like Avalonia, which were a bit very basic at the time I first wrote this, which meant you were pretty much limited to web or server stuff.) Over time, many APIs have been added to .NET Core, so much so that after version 3.1, .NET Core will jump to version 5.0, be known as .NET 5.0 without the "Core", and that then will be the future of the .NET Framework. What used to be the full .NET Framework will linger around in maintenance mode as Full .NET Framework 4.8.x for a few decades, until it will die (maybe there are still going to be some upgrades, but I doubt it). In other words, .NET Core is the future of .NET, and Full .NET Framework will go the way of the Dodo/Silverlight/WindowsPhone.

The main point of .NET Core, apart from multi-platform support, is to improve performance, and to enable "native compilation"/self-contained-deployment (so you don't need .NET framework/VM installed on the target machine.
On the one hand, this means docker.io support on Linux, and on the other, self-contained deployment is useful in "cloud-computing", since then you can just use whatever version of the dotnet-CORE framework you like, and you don't have to worry about which version(s) of the .NET framework the sysadmin has actually installed.

While the .NET Core runtime supports multiple operating systems and processors, the SDK is a different story. And while the SDK supports multiple OS, ARM support for the SDK is/was still work in progress. .NET Core is supported by Microsoft. Dotnet-Core did not come with WinForms or WPF or anything like that.

  • As of version 3.0, WinForms and WPF is also supported by .NET Core, but only on Windows, and only by C#. Not by VB.NET (VB.NET support planned for v5 in 2020). And there is no Forms Designer in .NET Core: it's being shipped with a Visual Studio update later, at an unspecified time.
  • WebForms are still not supported by .NET Core, and there are no plans to support them, ever (Blazor is the new kid in town for that).
  • .NET Core also comes with System.Runtime, which replaces mscorelib.
  • Oftentimes, .NET Core is mixed up with NetStandard, which is a bit of a wrapper around System.Runtime/mscorelib (and some others), that allows you to write libraries that target .NET Core, Full .NET Framework and Xamarin (iOS/Android), all at the same time.
  • the .NET Core SDK does not/did not work on ARM, at least not last time I checked.

"The Mono Project" is much older than .NET Core.
Mono is Spanish and means Monkey, and as a side-remark, the name has nothing to do with mononucleosis (hint: you could get a list of staff under http://primates.ximian.com/).
Mono was started in 2005 by Miguel de Icaza (the guy that started GNOME - and a few others) as an implementation of the .NET Framework for Linux (Ximian/SuSe/Novell). Mono includes Web-Forms, Winforms, MVC, Olive, and an IDE called MonoDevelop (also knows as Xamarin Studio or Visual Studio Mac). Basically the equivalent of (OpenJDK) JVM and (OpenJDK) JDK/JRE (as opposed to SUN/Oracle JDK). You can use it to get ASP.NET-WebForms + WinForms + ASP.NET-MVC applications to work on Linux.

Mono is supported by Xamarin (the new company name of what used to be Ximian, when they focused on the Mobile market, instead of the Linux market), and not by Microsoft.
(since Xamarin was bought by Microsoft, that's technically [but not culturally] Microsoft.)
You will usually get your C# stuff to compile on mono, but not the VB.NET stuff.
Mono misses some advanced features, like WSE/WCF and WebParts.
Many of the Mono implementations are incomplete (e.g. throw NotImplementedException in ECDSA encryption), buggy (e.g. ODBC/ADO.NET with Firebird), behave differently than on .NET (for example XML-serialization) or otherwise unstable (ASP.NET MVC) and unacceptably slow (Regex). On the upside, the Mono toolchain also works on ARM.

As far as .NET Core is concerned, when they say cross-platform, don't expect that cross-platform means that you could actually just apt-get install .NET Core on ARM-Linux, like you can with ElasticSearch. You'll have to compile the entire framework from source.
That is, if you have that space (e.g. on a Chromebook, which has a 16 to 32 GB total HD).
It also used to have issues of incompatibility with OpenSSL 1.1 and libcurl.
Those have been rectified in the latest version of .NET Core Version 2.2.
So much for cross-platform.

I found a statement on the official site that said, "Code written for it is also portable across application stacks, such as Mono".

As long as that code doesn't rely on WinAPI-calls, Windows-dll-pinvokes, COM-Components, a case-insensitive file system, the default-system-encoding (codepage) and doesn't have directory separator issues, that's correct. However, .NET Core code runs on .NET Core, and not on Mono. So mixing the two will be difficult. And since Mono is quite unstable and slow (for web applications), I wouldn't recommend it anyway. Try image-processing on .NET core, e.g. WebP or moving GIF or multipage-tiff or writing text on an image, you'll be nastily surprised.

Note:
As of .NET Core 2.0, there is System.Drawing.Common (NuGet), which contains most of the functionality of System.Drawing. It should be more or less feature-complete in .NET-Core 2.1. However, System.Drawing.Common uses GDI+, and therefore won't work on Azure (System.Drawing libraries are available in Azure Cloud Service [basically just a VM], but not in Azure Web App [basically shared hosting?])
So far, System.Drawing.Common works fine on Linux/Mac, but has issues on iOS/Android - if it works at all, there.
Prior to .NET Core 2.0, that is to say sometime mid-February 2017, you could use SkiaSharp for imaging (example) (you still can).
Post .net-core 2.0, you'll notice that SixLabors ImageSharp is the way to go, since System.Drawing is not necessarely secure, and has a lot of potential or real memory leaks, which is why you shouldn't use GDI in web-applications; Note that SkiaSharp is a lot faster than ImageSharp, because it uses native-libraries (which can also be a drawback). Also, note that while GDI+ works on Linux & Mac, that doesn't mean it works on iOS/Android.

Code not written for .NET (non-Core) is not portable to .NET Core.
Meaning, if you want a non-GPL C# library like PDFSharp to create PDF-documents (very commonplace), you're out of luck (at the moment) (not anymore). Never mind ReportViewer control, which uses Windows-pInvokes (to encrypt, create mcdf documents via COM, and to get font, character, kerning, font embedding information, measure strings and do line-breaking, and for actually drawing tiffs of acceptable quality), and doesn't even run on Mono on Linux
(I'm working on that).

Also, code written in .NET Core is not portable to Mono, because Mono lacks the .NET Core runtime libraries (so far).

My goal is to use C#, LINQ, EF7, visual studio to create a website that can be ran/hosted in linux.

EF in any version that I tried so far was so goddamn slow (even on such simple things like one table with one left-join), I wouldn't recommend it ever - not on Windows either.
I would particularly not recommend EF if you have a database with unique-constrains, or varbinary/filestream/hierarchyid columns. (Not for schema-update either.)
And also not in a situation where DB-performance is critical (say 10+ to 100+ concurrent users).
Also, running a website/web-application on Linux will sooner or later mean you'll have to debug it.
There is no debugging support for .NET Core on Linux. (Not anymore, but requires JetBrains Rider.)
MonoDevelop does not (yet) support debugging .NET Core projects.
If you have problems, you're on your own. You'll have to use extensive logging.
Be careful, be advised extensive logging will fill your disk in no time, particularly if your program enters an infinite loop or recursion.
This is especially dangerous if your web-app runs as root, because log-in requires logfile-space - if there's no free space left, you won't be able to login anymore.
(Normally, about 5% of diskspace is reserved for user root [aka administrator on Windows], so at least the administrator can still log in if the disk is almost full. But if your applications run as root, that restriction does not apply for their disk usage, and so their logfiles can use 100% of the remaining free space, so not even the administrator can log in any more.)
It's therefore better not to encrypt that disk, that is, if you value your data/system.

Someone told me that he wanted it to be "in Mono", but I don't know what that means.

It either means he doesn't want to use .NET Core, or he just wants to use C# on Linux/Mac. My guess is he just wants to use C# for a Web-App on Linux. .NET Core is the way to go for that, if you absolutely want to do it in C#. Don't go with "Mono proper"; on the surface, it would seem to work at first - but believe me you will regret it because Mono's ASP.NET MVC isn't stable when your server runs long-term (longer than 1 day) - you have now been warned. See also the "did not complete" references when measuring Mono performance on the techempower benchmarks.

fortunes

I know I want to use the .Net Core 1.0 framework with the technologies I listed above. He also said he wanted to use "fast cgi". I don't know what that means either.

It means he wants to use a high-performance full-featured WebServer like nginx (Engine-X), possibly Apache.
Then he can run mono/dotnetCore with virtual name based hosting (multiple domain names on the same IP) and/or load-balancing. He can also run other websites with other technologies, without requiring a different port-number on the web-server. It means your website runs on a fastcgi-server, and nginx forwards all web-requests for a certain domain via the fastcgi-protocol to that server. It also means your website runs in a fastcgi-pipeline, and you have to be careful what you do, e.g. you can't use HTTP 1.1 when transmitting files.
Otherwise, files will be garbled at the destination.
See also here and here.

To conclude:
.NET Core at present (2016-09-28) is not really portable, nor is is really cross-platform (in particular the debug-tools).
Nor is native-compilation easy, especially for ARM.
And to me, it also does not look like its development is "really finished", yet.
For example, System.Data.DataTable/DataAdaper.Update is missing... (not anymore with .NET Core 2.0)
Together with the System.Data.Common.IDB* interfaces. (not anymore with .NET Core 1.1)
if there ever was one class that is often used, DataTable/DataAdapter would be it...
Also, the Linux-installer (.deb) fails, at least on my machine, and I'm sure I'm not the only one that has that problem.
Debug, maybe with Visual Studio Code, if you can build it on ARM (I managed to do that - do NOT follow Scott Hanselman's blog-post if you do that - there's a howto in the wiki of VS-Code on github), because they don't offer the executable.
Yeoman also fails. (I guess it has something to do with the nodejs version you installed - VS Code requires one version, Yeoman another... but it should run on the same computer. pretty lame
Never mind that it should run on the node version shipped by default on the OS.
Never mind that there should be no dependency on NodeJS in the first place.
The kestell server is also work in progress.
And judging by my experience with the mono-project, I highly doubt they ever tested .NET Core on FastCGI, or that they have any idea what FastCGI-support means for their framework, let alone that they tested it to make sure "everything works". In fact, I just tried making a fastcgi-application with .NET Core and just realized there is no FastCGI library for .NET Core "RTM"...

So when you're going to run .NET Core "RTM" behind nginx, you can only do it by proxying requests to kestrell (that semi-finished nodeJS-derived web-server) - there's no fastcgi support at present in .NET Core "RTM", AFAIK. Since there is no .net core fastcgi library, and no samples, it's also highly unlikely that anybody did any testing on the framework to make sure fastcgi works as expected.

I also question the performance.
In the (preliminary) techempower-benchmark (round 13), aspnetcore-linux ranks on 25% relative to the best performance, while comparable frameworks like Go (golang) rank at 96.9% of peak performance (and that is when returning plaintext without file-system access only). .NET Core does a little better on JSON-serialization, but it does not look compelling either (go reaches 98.5% of peak, .NET core 65%). That said, it can't possibly be worse than "mono proper".

Also, since it's still relatively new, not all of the major libraries have been ported (yet), and I doubt that some of them will ever be ported.
Imaging support is also questionable at best.
For anything encryption, use BouncyCastle instead.

Can you help me make sense of all these terms and if my expectations are realistic?

I hope i helped you making more sense with all these terms.
As far as your expecations go:
Developing a Linux application without knowing anything about Linux is a really stupid idea in the first place, and it's also bound to fail in some horrible way one way or the other. That said, because Linux comes at no licensing costs, it's a good idea in principle, BUT ONLY IF YOU KNOW WHAT YOU DO.
Developing an application for a platform where you can't debug your application on is another really bad idea.
Developing for fastcgi without knowing what consequences there are is yet another really bad idea.

Doing all these things on a "experimental" platform without any knowledge of that platform's specifics and without debugging support is suicide, if your project is more than just a personal homepage. On the other hand, I guess doing it with your personal homepage for learning purposes would probably be a very good experience - then you get to know what the framework and what the non-framework problems are.
You can for example (programmatically) loop-mount a case-insensitive fat32, hfs or JFS for your application, to get around the case-sensitivity issues (loop-mount not recommended in production).

To summarize
At present (2016-09-28), I would stay away from .NET Core (for production usage). Maybe in one to two years, you can take another look, but probably not before.
If you have a new web-project that you develop, start it in .NET Core, not mono.

If you want a framework that works on Linux (x86/AMD64/ARMhf) and Windows and Mac, that has no dependencies, i.e. only static linking and no dependency on .NET, Java or Windows, use Golang instead. It's more mature, and its performance is proven (Baidu uses it with 1 million concurrent users), and golang has a significantly lower memory footprint. Also golang is in the repositories, the .deb installs without problems, the sourcecode compiles - without requiring changes - and golang (in the meantime) has debugging support with delve and JetBrains Gogland on Linux (and Windows and Mac). Golang's build process (and runtime) also doesn't depend on NodeJS, which is yet another plus.

As far as mono goes, stay away from it.
It is nothing short of amazing how far mono has come, but unfortunately that's no substitute for its performance/scalability and stability issues for production applications.
Also, mono-development is quite dead, they largely only develop the parts relevant to Android and iOS anymore, because that's where Xamarin makes their money.
Don't expect Web-Development to be a first-class Xamarin/mono citizen.
.NET Core might be worth it, if you start a new project, but for existing large web-forms projects, porting over is largely out of the question, the changes required are huge. If you have a MVC-project, the amount of changes might be manageable, if your original application design was sane, which is mostly not the case for most existing so-called "historically grown" applications.

December 2016 Update:
Native compilation has been removed from .NET Core preview, as it is not yet ready...

Seems like they have improved pretty heavily on the raw text-file benchmark, but on the other hand, it's gotten pretty buggy. Also, it further deteriorated in the JSON benchmarks. Curious also that entity framework shall be faster for updates than Dapper - although both at record slowness. This is very unlikely to be true. Looks like there still are more than just a few bugs to hunt.

Also, there seems to be relief coming on the Linux IDE front.
JetBrains released "Project Rider", an early access preview of a C#/.NET Core IDE for Linux (and Mac and Windows), that can handle Visual Studio Project files. Finally a C# IDE that is usable & that isn't slow as hell.

Conclusion: .NET Core still is pre-release quality software as we march into 2017. Port your libraries, but stay away from it for production usage, until framework quality stabilizes.
And keep an eye on Project Rider.

buggy .net core

2017 Update
Have migrated my (brother's) homepage to .NET Core for now.
So far, the runtime on Linux seems to be stable enough (at least for small projects) - it survived a load test with ease - mono never did.
Also, it looks like I mixed up .NET-Core-native and .NET-Core-self-contained-deployment. Self-contained deployment works, but it is a bit underdocumented, although it's super easy (the build/publish tools are a bit unstable, yet - if you encounter "Positive number required. - Build FAILED." - run the same command again, and it works).

You can run

dotnet restore -r win81-x64
dotnet build -r win81-x64
dotnet publish -f netcoreapp1.1 -c Release -r win81-x64

Note: As per .NET Core 3, you can publish everything minified as a single file:

dotnet publish -r win-x64 -c Release /p:PublishSingleFile=true
dotnet publish -r linux-x64 -c Release /p:PublishSingleFile=true

However, unlike go, it's not a statically linked executable, but a self-extracting zip file, so when deploying, you might run into problems, especially if the temp directory is locked down by group policy, or some other issues. Works fine for a hello-world program, though. And if you don't minify, the executable size will clock in at something around 100 MB.

And you get a self-contained .exe-file (in the publish directory), which you can move to a Windows 8.1 machine without .NET framework installed and let it run. Nice. It's here that dotNET-Core just starts to get interesting. (mind the gaps, SkiaSharp doesn't work on Windows 8.1 / Windows Server 2012 R2, [yet] - the ecosystem has to catch up first - but interestingly, the Skia-dll-load-fail doesn't crash the entire server/application - so everything else works)

(Note: SkiaSharp on Windows 8.1 is missing the appropriate VC runtime files - msvcp140.dll and vcruntime140.dll. Copy them into the publish-directory, and Skia will work on Windows 8.1.)

August 2017 Update
.NET Core 2.0 released.
Be careful - comes with (huge breaking) changes in authentication...
On the upside, it brought the DataTable/DataAdaper/DataSet classes back, and many more.
Realized .NET Core is still missing support for Apache SparkSQL, because Mobius isn't yet ported. That's bad, because that means no SparkSQL support for my IoT Cassandra Cluster, so no joins...
Experimental ARM support (runtime only, not SDK - too bad for devwork on my Chromebook - looking forward to 2.1 or 3.0).
PdfSharp is now experimentally ported to .NET Core.
JetBrains Rider left EAP. You can now use it to develop & debug .NET Core on Linux - though so far only .NET Core 1.1 until the update for .NET Core 2.0 support goes live.

May 2018 Update
.NET Core 2.1 release imminent. Maybe this will fix NTLM-authentication on Linux (NTLM authentication doesn't work on Linux {and possibly Mac} in .NET-Core 2.0 with multiple authenticate headers, such as negotiate, commonly sent with ms-exchange, and they're apparently only fixing it in v2.1, no bugfix release for 2.0).
But I'm not installing preview releases on my machine. So waiting.
v2.1 is also said to greatly reduce compile times. That would be good.

Also, note that on Linux, .NET Core is 64-Bit only !
There is no, and there will be no, x86-32 version of .NET Core on Linux.
And the ARM port is ARM-32 only. No ARM-64, yet.
And on ARM, you (at present) only have the runtime, not the dotnet-SDK.

And one more thing:
Because .NET-Core uses OpenSSL 1.0, .NET Core on Linux doesn't run on Arch Linux, and by derivation not on Manjaro (the most popular Linux distro by far at this point in time), because Arch Linux uses OpenSSL 1.1. So if you're using Arch Linux, you're out of luck (with Gentoo, too).

Edit:

Latest version of .NET Core 2.2+ supports OpenSSL 1.1. So you can use it on Arch or (k)Ubuntu 19.04+. You might have to use the .NET-Core install script though, because there are no packages, yet.

On the upside, performance has definitely improved: fortunes

plaintext

.NET Core 3:
.NET-Core v 3.0 is said to bring WinForms and WPF to .NET-Core.
However, while WinForms and WPF will be .NET Core, WinForms and WPF in .NET-Core will run on Windows only, because WinForms/WPF will use the Windows-API.

Note:
.NET Core 3.0 is now out (RTM), and there is WinForms and WPF support, but only for C# (on Windows). There is no WinForms-Core-Designer. The designer will, eventually, come with a Visual Studio update, somewhen. WinForms support for VB.NET is not supported, but is planned for .NET 5.0 somewhen in 2020.

PS:

echo "DOTNET_CLI_TELEMETRY_OPTOUT=1" >> /etc/environment
export DOTNET_CLI_TELEMETRY_OPTOUT=1 

If you've used it on windows, you probably never saw this:

The .NET Core tools collect usage data in order to improve your experience.
The data is anonymous and does not include command-line arguments.
The data is collected by Microsoft and shared with the community.
You can opt out of telemetry by setting a DOTNET_CLI_TELEMETRY_OPTOUT environment variable to 1 using your favorite shell.
You can read more about .NET Core tools telemetry @ https://aka.ms/dotnet-cli-telemetry.

I thought I'd mention that I think monodevelop (aka Xamarin Studio, the Mono IDE, or Visual Studio Mac as it is now called on Mac) has evolved quite nicely, and is - in the meantime - largely usable.
However, JetBrains Rider (2018 EAP at this point in time) is definitely a lot nicer and more reliable (and the included decompiler is a life-safer), that is to say, if you develop .NET-Core on Linux or Mac. MonoDevelop does not support Debug-StepThrough on Linux in .NET Core, though, since MS does not license their debugging API dll (except for VisualStudio Mac ... ). However, you can use the Samsung debugger for .NET Core through the .NET Core debugger extension for Samsung Debugger for MonoDevelop

Disclaimer:
I don't use Mac, so I can't say if what I wrote here applies to FreeBSD-Unix based Mac as well. I am refering to the Linux (Debian/Ubuntu/Mint) version of JetBrains Rider, mono, MonoDevelop/VisualStudioMac/XamarinStudio and .NET-Core. Also, Apple is contemplating a move from Intel-processors to self-manufactured ARM(ARM-64?)-based processors, so much of what applies to Mac right now might not apply to Mac in the future (2020+).

Also, when I write "mono is quite unstable and slow", the unstable relates to WinFroms & WebForms applications, specifically executing web-applications via fastcgi or with XSP (on the 4.x version of mono), as well as XML-serialization-handling peculiarities, and the quite-slow relates to WinForms, and regular expressions in particular (ASP.NET-MVC uses regular expressions for routing as well).

When I write about my experience about mono 2.x, 3.x and 4.x, that also does not necessarely mean these issues haven't been resolved by now, or by the time you are reading this, nor that if they are fixed now, that there can't be a regression later that reintroduces any of these bugs/features. Nor does that mean that if you embed the mono-runtime, you'll get the same results as when you use the (dev) system's mono runtime. It also doesn't mean that embedding the mono-runtime (anywhere) is necessarely free.

All that doesn't necessarely mean mono is ill-suited for iOS or Android, or that it has the same issues there. I don't use mono on Android or IOS, so I'm in no positon to say anything about stability, usability, costs and performance on these platforms. Obviously, if you use .NET on Android, you have some other costs considerations to do as well, such as weighting xamarin-costs vs. costs and time for porting existing code to Java. One hears mono on Android and IOS shall be quite good. Take it with a grain of salt. For one, don't expect the default-system-encoding to be the same on android/ios vs. Windows, and don't expect the android filesystem to be case-insensitive, and don't expect any windows fonts to be present.

Fiddler not capturing traffic from browsers

Same problem here, in all browsers (IE, Chrome, FF). Upon startup the Fiddler Log tab showed the following:

"!WARNING Fiddler has detected that system or domain Group Policy has set ProxySettingsPerUser to 0. Unless Fiddler is run Elevated (e.g. Run As Administrator), it may not capture traffic from Internet Explorer and other programs. Current process IS running Elevated."

I'm in a huge corporate environment, with no connection to or info about group policy changes; it apparently just got applied one day. Thanks, bureaucracy :)

Anyway, that led me to messing around with IE proxy settings. Changing it from Automatic to 127.0.0.1 on port 8888 (the default configured port in Fiddler) worked. Kind of a pain, though, because I have to set it each time to override the group policy setting. And then I get cert errors, which is a known thing because Fiddler uses it's own, untrusted cert . . . and the beat goes on . . .