Programs & Examples On #Scjp

SCJP is a certification for programmers experienced using the Java programming language. SCJP affirms that the programmer really knows how to code in Java. However the ability to design and implement a complete application is not affirmed by this test (it is affirmed by the second step certification, SCJD).

Are static methods inherited in Java?

This concept is not that easy as it looks. We can access static members without inheritance, which is HasA-relation. We can access static members by extending the parent class also. That doesn't imply that it is an ISA-relation (Inheritance). Actually static members belong to the class, and static is not an access modifier. As long as the access modifiers permit to access the static members we can use them in other classes. Like if it is public then it will be accessible inside the same package and also outside the package. For private we can't use it anywhere. For default, we can use it only within the package. But for protected we have to extend the super class. So getting the static method to other class does not depend on being Static. It depends on Access modifiers. So, in my opinion, Static members can access if the access modifiers permit. Otherwise, we can use them like we use by Hasa-relation. And has a relation is not inheritance. Again we can not override the static method. If we can use other method but cant override it, then it is HasA-relation. If we can't override them it won't be inheritance.So the writer was 100% correct.

Why can't overriding methods throw exceptions broader than the overridden method?

What explanation do we attribute to the below

class BaseClass {

    public  void print() {
        System.out.println("In Parent Class , Print Method");
    }

    public static void display() {
        System.out.println("In Parent Class, Display Method");
    }

}


class DerivedClass extends BaseClass {

    public  void print() throws Exception {
        System.out.println("In Derived Class, Print Method");
    }

    public static void display() {
        System.out.println("In Derived Class, Display Method");
    }
}

Class DerivedClass.java throws a compile time exception when the print method throws a Exception , print () method of baseclass does not throw any exception

I am able to attribute this to the fact that Exception is narrower than RuntimeException , it can be either No Exception (Runtime error ), RuntimeException and their child exceptions

Efficiency of Java "Double Brace Initialization"?

To create sets you can use a varargs factory method instead of double-brace initialisation:

public static Set<T> setOf(T ... elements) {
    return new HashSet<T>(Arrays.asList(elements));
}

The Google Collections library has lots of convenience methods like this, as well as loads of other useful functionality.

As for the idiom's obscurity, I encounter it and use it in production code all the time. I'd be more concerned about programmers who get confused by the idiom being allowed to write production code.

Visual Studio popup: "the operation could not be completed"

The error can also happen if you're in the folder in Windows Explorer or another app as you try to delete it from VS or have the file opened in another app. Windows has the habit of locking folders and files, especially on networked machines. It is possible to break the lock by using Process Explorer occasionally, but the simplest thing to do is to get out of the folder or close the file in question.

creating triggers for After Insert, After Update and After Delete in SQL

(Update: overlooked a fault in the matter, I have corrected)

(Update2: I wrote from memory the code screwed up, repaired it)

(Update3: check on SQLFiddle)

create table Derived_Values
  (
    BusinessUnit nvarchar(100) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)
    )

go

ALTER TABLE Derived_Values ADD CONSTRAINT PK_Derived_Values
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

create table Derived_Values_Test
  (
    BusinessUnit nvarchar(150)
    ,Questions nvarchar(100)
    ,Answer nvarchar(100)
    )

go

CREATE TRIGGER trgAfterUpdate ON  [Derived_Values]
FOR UPDATE
AS  
begin
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Updated Record -- After Update Trigger.'

    insert into 
        [Derived_Values_Test]
        --(BusinessUnit,Questions, Answer) 
    SELECT 
        @BusinessUnit + i.BusinessUnit, i.Questions, i.Answer
    FROM 
        inserted i
        inner join deleted d on i.BusinessUnit = d.BusinessUnit
end

go

CREATE TRIGGER trgAfterDelete ON  [Derived_Values]
FOR UPDATE
AS  
begin
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Deleted Record -- After Delete Trigger.'

    insert into 
        [Derived_Values_Test]
        --(BusinessUnit,Questions, Answer) 
    SELECT 
        @BusinessUnit + d.BusinessUnit, d.Questions, d.Answer
    FROM 
        deleted d
end

go

insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q11', 'A11')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q12', 'A12')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q21', 'A21')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q22', 'A22')

UPDATE Derived_Values SET Answer='Updated Answers A11' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q11');
UPDATE Derived_Values SET Answer='Updated Answers A12' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q12');
UPDATE Derived_Values SET Answer='Updated Answers A21' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q21');
UPDATE Derived_Values SET Answer='Updated Answers A22' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q22');

delete Derived_Values;

and then:

SELECT * FROM Derived_Values;
go

select * from Derived_Values_Test;


Record Count: 0;

BUSINESSUNIT    QUESTIONS   ANSWER
Updated Record -- After Update Trigger.BU1  Q11 Updated Answers A11
Deleted Record -- After Delete Trigger.BU1  Q11 A11
Updated Record -- After Update Trigger.BU1  Q12 Updated Answers A12
Deleted Record -- After Delete Trigger.BU1  Q12 A12
Updated Record -- After Update Trigger.BU2  Q21 Updated Answers A21
Deleted Record -- After Delete Trigger.BU2  Q21 A21
Updated Record -- After Update Trigger.BU2  Q22 Updated Answers A22
Deleted Record -- After Delete Trigger.BU2  Q22 A22

(Update4: If you want to sync: SQLFiddle)

create table Derived_Values
  (
    BusinessUnit nvarchar(100) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)
    )

go

ALTER TABLE Derived_Values ADD CONSTRAINT PK_Derived_Values
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

create table Derived_Values_Test
  (
    BusinessUnit nvarchar(150) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)
    )

go

ALTER TABLE Derived_Values_Test ADD CONSTRAINT PK_Derived_Values_Test
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

CREATE TRIGGER trgAfterInsert ON  [Derived_Values]
FOR INSERT
AS  
begin
    insert
        [Derived_Values_Test]
        (BusinessUnit,Questions,Answer)
    SELECT 
        i.BusinessUnit, i.Questions, i.Answer
    FROM 
        inserted i
end

go


CREATE TRIGGER trgAfterUpdate ON  [Derived_Values]
FOR UPDATE
AS  
begin
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Updated Record -- After Update Trigger.'

    update
        [Derived_Values_Test]
    set
        --BusinessUnit = i.BusinessUnit
        --,Questions = i.Questions
        Answer = i.Answer
    from
        [Derived_Values]
        inner join inserted i 
    on
        [Derived_Values].BusinessUnit = i.BusinessUnit
        and
        [Derived_Values].Questions = i.Questions
end

go

CREATE TRIGGER trgAfterDelete ON  [Derived_Values]
FOR DELETE
AS  
begin
    delete 
        [Derived_Values_Test]
    from
        [Derived_Values_Test]
        inner join deleted d 
    on
        [Derived_Values_Test].BusinessUnit = d.BusinessUnit
        and
        [Derived_Values_Test].Questions = d.Questions
end

go

insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q11', 'A11')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q12', 'A12')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q21', 'A21')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q22', 'A22')

UPDATE Derived_Values SET Answer='Updated Answers A11' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q11');
UPDATE Derived_Values SET Answer='Updated Answers A12' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q12');
UPDATE Derived_Values SET Answer='Updated Answers A21' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q21');
UPDATE Derived_Values SET Answer='Updated Answers A22' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q22');

--delete Derived_Values;

And then:

SELECT * FROM Derived_Values;
go

select * from Derived_Values_Test;


BUSINESSUNIT    QUESTIONS   ANSWER
BU1 Q11 Updated Answers A11
BU1 Q12 Updated Answers A12
BU2 Q21 Updated Answers A21
BU2 Q22 Updated Answers A22

BUSINESSUNIT    QUESTIONS   ANSWER
BU1 Q11 Updated Answers A11
BU1 Q12 Updated Answers A12
BU2 Q21 Updated Answers A21
BU2 Q22 Updated Answers A22

Git push error: Unable to unlink old (Permission denied)

If you are using any IDE most likely the problem is that file was used by some process. Like your tomcat might be using the file. Try to identify that particular process and close it. That should solve your problem.

Split list into smaller lists (split in half)

Another take on this problem in 2020 ... Here's a generalization of the problem. I interpret the 'divide a list in half' to be .. (i.e. two lists only and there shall be no spillover to a third array in case of an odd one out etc). For instance, if the array length is 19 and a division by two using // operator gives 9, and we will end up having two arrays of length 9 and one array (third) of length 1 (so in total three arrays). If we'd want a general solution to give two arrays all the time, I will assume that we are happy with resulting duo arrays that are not equal in length (one will be longer than the other). And that its assumed to be ok to have the order mixed (alternating in this case).

"""
arrayinput --> is an array of length N that you wish to split 2 times
"""
ctr = 1 # lets initialize a counter

holder_1 = []
holder_2 = []

for i in range(len(arrayinput)): 

    if ctr == 1 :
        holder_1.append(arrayinput[i])
    elif ctr == 2: 
        holder_2.append(arrayinput[i])

    ctr += 1 

    if ctr > 2 : # if it exceeds 2 then we reset 
        ctr = 1 

This concept works for any amount of list partition as you'd like (you'd have to tweak the code depending on how many list parts you want). And is rather straightforward to interpret. To speed things up , you can even write this loop in cython / C / C++ to speed things up. Then again, I've tried this code on relatively small lists ~ 10,000 rows and it finishes in a fraction of second.

Just my two cents.

Thanks!

Required maven dependencies for Apache POI to work

I used the below dependency. If you are using Selenium then it's good to use all of them as below. Else you will see some errors and then do the reserch and add some more dependencies.

<dependency>
                 <groupId>org.apache.poi</groupId>
                 <artifactId>poi</artifactId>
                 <version>3.9</version>
          </dependency>
          <dependency>
                 <groupId>org.apache.poi</groupId>
                 <artifactId>poi-ooxml</artifactId>
                 <version>3.9</version>
          </dependency>
          <dependency>
                 <groupId>org.apache.poi</groupId>
                 <artifactId>poi-ooxml-schemas</artifactId>
                 <version>3.9</version>
          </dependency>
          <dependency>
                 <groupId>org.apache.poi</groupId>
                 <artifactId>poi-scratchpad</artifactId>
                 <version>3.9</version>
          </dependency>
          <dependency>
                 <groupId>org.apache.poi</groupId>
                 <artifactId>ooxml-schemas</artifactId>
                 <version>1.1</version>
          </dependency>

          <dependency>
                 <groupId>org.apache.poi</groupId>
                 <artifactId>openxml4j</artifactId>
                 <version>1.0-beta</version>
          </dependency>

Why am I getting a " Traceback (most recent call last):" error?

At the beginning of your file you set raw_input to 0. Do not do this, at it modifies the built-in raw_input() function. Therefore, whenever you call raw_input(), it is essentially calling 0(), which raises the error. To remove the error, remove the first line of your code:

M = 1.6
# Miles to Kilometers 
# Celsius Celsius = (var1 - 32) * 5/9
# Gallons to liters Gallons = 3.6
# Pounds to kilograms Pounds = 0.45
# Inches to centimete Inches = 2.54


def intro():
    print("Welcome! This program will convert measures for you.")
    main()

def main():
    print("Select operation.")
    print("1.Miles to Kilometers")
    print("2.Fahrenheit to Celsius")
    print("3.Gallons to liters")
    print("4.Pounds to kilograms")
    print("5.Inches to centimeters")

    choice = input("Enter your choice by number: ")

    if choice == '1':
        convertMK()

    elif choice == '2':
        converCF()

    elif choice == '3':
        convertGL()

    elif choice == '4':
        convertPK()

    elif choice == '5':
        convertPK()

    else:
        print("Error")


def convertMK():
    input_M = float(raw_input(("Miles: ")))
    M_conv = (M) * input_M
    print("Kilometers: %f\n" % M_conv)
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print("I didn't quite understand that answer. Terminating.")
        main()

def converCF():
    input_F = float(raw_input(("Fahrenheit: ")))
    F_conv = (input_F - 32) * 5/9
    print("Celcius: %f\n") % F_conv
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print("I didn't quite understand that answer. Terminating.")
        main()

def convertGL():
    input_G = float(raw_input(("Gallons: ")))
    G_conv = input_G * 3.6
    print("Centimeters: %f\n" % G_conv)
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print ("I didn't quite understand that answer. Terminating.")
        main()

def convertPK():
    input_P = float(raw_input(("Pounds: ")))
    P_conv = input_P * 0.45
    print("Centimeters: %f\n" % P_conv)
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print ("I didn't quite understand that answer. Terminating.")
        main()

def convertIC():
    input_cm = float(raw_input(("Inches: ")))
    inches_conv = input_cm * 2.54
    print("Centimeters: %f\n" % inches_conv)
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print ("I didn't quite understand that answer. Terminating.")
        main()

def end():
    print("This program will close.")
    exit()

intro()

How to set the text color of TextView in code?

I believe that if you want to specify a color as a resource (in the XML file), you'll have to provide its ARGB value (not simply the RGB value).

Try changing your color value to #FFFF0000. It should give you RED.

How do I reference tables in Excel using VBA?

A "table" in Excel is indeed known as a ListObject.

The "proper" way to reference a table is by getting its ListObject from its Worksheet i.e. SheetObject.ListObjects(ListObjectName).

If you want to reference a table without using the sheet, you can use a hack Application.Range(ListObjectName).ListObject.

NOTE: This hack relies on the fact that Excel always creates a named range for the table's DataBodyRange with the same name as the table. However this range name can be changed...though it's not something you'd want to do since the name will reset if you edit the table name! Also you could get a named range with no associated ListObject.

Given Excel's not-very-helpful 1004 error message when you get the name wrong, you may want to create a wrapper...

Public Function GetListObject(ByVal ListObjectName As String, Optional ParentWorksheet As Worksheet = Nothing) As Excel.ListObject
On Error Resume Next

    If (Not ParentWorksheet Is Nothing) Then
        Set GetListObject = ParentWorksheet.ListObjects(ListObjectName)
    Else
        Set GetListObject = Application.Range(ListObjectName).ListObject
    End If

On Error GoTo 0 'Or your error handler

    If (Not GetListObject Is Nothing) Then
        'Success
    ElseIf (Not ParentWorksheet Is Nothing) Then
        Call Err.Raise(1004, ThisWorkBook.Name, "ListObject '" & ListObjectName & "' not found on sheet '" & ParentWorksheet.Name & "'!")
    Else
        Call Err.Raise(1004, ThisWorkBook.Name, "ListObject '" & ListObjectName & "' not found!")
    End If

End Function

Also some good ListObject info here.

Displaying a webcam feed using OpenCV and Python

Try the following. It is simple, but I haven't figured out a graceful way to exit yet.

import cv2.cv as cv
import time

cv.NamedWindow("camera", 0)

capture = cv.CaptureFromCAM(0)

while True:
    img = cv.QueryFrame(capture)
    cv.ShowImage("camera", img)
    if cv.WaitKey(10) == 27:
        break
cv.DestroyAllWindows()

How does += (plus equal) work?

a += b is shorthand for a = a +b which means:

1) 1 += 2 // won't compile

2) 15

How to listen for 'props' changes

You can watch props to execute some code upon props changes:

_x000D_
_x000D_
new Vue({_x000D_
  el: '#app',_x000D_
  data: {_x000D_
    text: 'Hello'_x000D_
  },_x000D_
  components: {_x000D_
    'child' : {_x000D_
      template: `<p>{{ myprop }}</p>`,_x000D_
      props: ['myprop'],_x000D_
      watch: { _x000D_
       myprop: function(newVal, oldVal) { // watch it_x000D_
          console.log('Prop changed: ', newVal, ' | was: ', oldVal)_x000D_
        }_x000D_
      }_x000D_
    }_x000D_
  }_x000D_
});
_x000D_
<script src="https://unpkg.com/vue/dist/vue.js"></script>_x000D_
_x000D_
<div id="app">_x000D_
  <child :myprop="text"></child>_x000D_
  <button @click="text = 'Another text'">Change text</button>_x000D_
</div>
_x000D_
_x000D_
_x000D_

appending list but error 'NoneType' object has no attribute 'append'

You are not supposed to assign it to any variable, when you append something in the list, it updates automatically. use only:-

last_list.append(p.last)

if you assign this to a variable "last_list" again, it will no more be a list (will become a none type variable since you haven't declared the type for that) and append will become invalid in the next run.

React - uncaught TypeError: Cannot read property 'setState' of undefined

  1. Check state check state whether you create particular property or not

_x000D_
_x000D_
this.state = {_x000D_
            name: "",_x000D_
            email: ""_x000D_
            }_x000D_
            _x000D_
           _x000D_
            _x000D_
this.setState(() => ({ _x000D_
             comments: comments          //comments not available in state_x000D_
             })) 
_x000D_
_x000D_
_x000D_

2.Check the (this) if you doing setState inside any function (i.e handleChange) check whether the function bind to this or the function should be arrow function .

## 3 ways for binding this to the below function##

_x000D_
_x000D_
//3 ways for binding this to the below function_x000D_
_x000D_
handleNameChange(e) {  _x000D_
     this.setState(() => ({ name }))_x000D_
    }_x000D_
    _x000D_
// 1.Bind while callling function_x000D_
      onChange={this.handleNameChange.bind(this)}_x000D_
      _x000D_
      _x000D_
//2.make it as arrow function_x000D_
     handleNameChange((e)=> {  _x000D_
     this.setState(() => ({ name }))_x000D_
     })_x000D_
    _x000D_
//3.Bind in constuctor _x000D_
_x000D_
constructor(props) {_x000D_
        super(props)_x000D_
        this.state = {_x000D_
            name: "",_x000D_
            email: ""_x000D_
        }_x000D_
        this.handleNameChange = this.handleNameChange.bind(this)_x000D_
        }
_x000D_
_x000D_
_x000D_

How to exclude a directory in find . command

i wanted to know the number of directories, files an MB of just the current directory - and that code does exactly what i want :-)

the source

- ...    2791037 Jun  2  2011 foo.jpg
- ... 1284734651 Mär 10 16:16 foo.tar.gz
- ...          0 Mär 10 15:28 foo.txt
d ...       4096 Mär  3 17:12 HE
d ...       4096 Mär  3 17:21 KU
d ...       4096 Mär  3 17:17 LE
d ...          0 Mär  3 17:14 NO
d ...          0 Mär  3 17:15 SE
d ...          0 Mär  3 17:13 SP
d ...          0 Mär  3 17:14 TE
d ...          0 Mär  3 19:20 UN

the code

format="%s%'12d\n"

find . -type d -not -path "./*/*" | wc -l | awk -v fmt=$format '{printf fmt, " Anzahl Ordner  = ", $1-1}'
find . -type f -not -path "./*/*" | wc -l | awk -v fmt=$format '{printf fmt, " Anzahl Dateien = ", $1}'
  du . -hmS --max-depth=0 | awk -v fmt=$format '{printf fmt, " Groesse (MB)   = ", $1}'

note: the extra format="%s%'12d\n" is necessary for awk to format the numbers.

the result

Anzahl Ordner  =            8
Anzahl Dateien =            3
Groesse (MB)   =        1.228

Shorter syntax for casting from a List<X> to a List<Y>?

In case when X derives from Y you can also use ToList<T> method instead of Cast<T>

listOfX.ToList<Y>()

Difference between Static methods and Instance methods

Instance methods => invoked on specific instance of a specific class. Method wants to know upon which class it was invoked. The way it happens there is a invisible parameter called 'this'. Inside of 'this' we have members of instance class already set with values. 'This' is not a variable. It's a value, you cannot change it and the value is reference to the receiver of the call. Ex: You call repairmen(instance method) to fix your TV(actual program). He comes with tools('this' parameter). He comes with specific tools needed for fixing TV and he can fix other things also.

In static methods => there is no such thing as 'this'. Ex: The same repairman (static method). When you call him you have to specify which repairman to call(like electrician). And he will come and fix your TV only. But, he doesn't have tools to fix other things (there is no 'this' parameter).

Static methods are usually useful for operations that don't require any data from an instance of the class (from 'this') and can perform their intended purpose solely using their arguments.

Java 8 Lambda filter by Lists

Look this:

List<Client> result = clients
    .stream()
    .filter(c -> 
        (users.stream().map(User::getName).collect(Collectors.toList())).contains(c.getName()))
        .collect(Collectors.toList());

Saving the PuTTY session logging

To set permanent PuTTY session parameters do:

  1. Create sessions in PuTTY. Name it as "MyskinPROD"

  2. Configure the path for this session to point to "C:\dir\&Y&M&D&T_&H_putty.log".

  3. Create a Windows "Shortcut" to C:...\Putty.exe.

  4. Open "Shortcut" Properties and append "Target" line with parameters as shown below:

    "C:\Program Files (x86)\UTL\putty.exe" -ssh -load MyskinPROD user@ServerIP -pw password
    

Now, your PuTTY shortcut will bring in the "MyskinPROD" configuration every time you open the shortcut.

Check the screenshots and details on how I did it in my environment:

http://www.evernote.com/shard/s184/sh/93ebf08f-fde2-4dad-bccf-961c98fb614b/983d2ff8f2d1e6184318825d68b0b829

How do I script a "yes" response for installing programs?

If you want to just accept defaults you can use:

\n | ./shell_being_run

Ruby array to string conversion

suppose your array :

arr=["1","2","3","4"]

Method to convert array to string:

Array_name.join(",")

Example:

arr.join(",")

Result:

"'1','2','3','4'"

Access Tomcat Manager App from different host

To access the tomcat manager from different machine you have to follow bellow steps:

1. Update conf/tomcat-users.xml file with user and some roles:

<role rolename="manager-gui"/>
 <role rolename="manager-script"/>
 <role rolename="manager-jmx"/>
 <role rolename="manager-status"/>
 <user username="admin" password="admin" roles="manager-gui,manager-script,manager-jmx,manager-status"/>

Here admin user is assigning roles="manager-gui,manager-script,manager-jmx,manager-status".

Here tomcat user and password is : admin

2. Update webapps/manager/META-INF/context.xml file (Allowing IP address):

Default configuration:

<Context antiResourceLocking="false" privileged="true" >
  
  <Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />
  
  <Manager sessionAttributeValueClassNameFilter="java\.lang\.(?:Boolean|Integer|Long|Number|String)|org\.apache\.catalina\.filters\.CsrfPreventionFilter\$LruCache(?:\$1)?|java\.util\.(?:Linked)?HashMap"/>
</Context>

Here in Valve it is allowing only local machine IP start with 127.\d+.\d+.\d+ .

2.a : Allow specefic IP:

<Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1|YOUR.IP.ADDRESS.HERE" />

Here you just replace |YOUR.IP.ADDRESS.HERE with your IP address

2.b : Allow all IP:

<Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow=".*" />

Here using allow=".*" you are allowing all IP.

Thanks :)

Uncaught TypeError: Cannot read property 'appendChild' of null

If this is happening to you in an AJAX post, you'll want to compare the values that you're sending and the values that the Controller is expecting.

In my case, I had changed a parameter in a serializable class from State to StateID, and then in an AJAX call didn't change the receiving field out 'data'

success: function (data) { MakeAddressForm.formData.StateID = data.State;

Note that the class was changed - it doesn't matter what I call it in the formData.

This created a null reference in the formData which I was trying to post back to the Controller once I'd done the update. Obviously, if someone changed the state (which was the purpose of the form) then they didn't get the error, so it made for a hard one to find.

This also through a 500 error. I'm posting this here in hopes it saves someone else the time I've wasted

Warning: The method assertEquals from the type Assert is deprecated

this method also encounter a deprecate warning:

org.junit.Assert.assertEquals(float expected,float actual) //deprecated

It is because currently junit prefer a third parameter rather than just two float variables input.

The third parameter is delta:

public static void assertEquals(double expected,double actual,double delta) //replacement

this is mostly used to deal with inaccurate Floating point calculations

for more information, please refer this problem: Meaning of epsilon argument of assertEquals for double values

Eclipse CDT: Symbol 'cout' could not be resolved

I am using Ubuntu 12.04 / Eclipse 4.2.1 / CDT 8.1.1 and I used to have the same problem for quite some time: importing a C++ project from SVN would cause these annoying "Unresolved inclusion" errors and I would instead have to create a new project and copy the files in there as a work-around (still partial, since SVN functionality would not be there!).

At last, I have just found a simple, satisfactory solution:

  • Go to Project -> Properties -> C/C++ General -> Preprocessor Include Paths, Macros etc. -> Providers and check Enable language settings providers for this project.

  • Restart Eclipse.

Hopefully that already does the trick.

How can jQuery deferred be used?

A deferred can be used in place of a mutex. This is essentially the same as the multiple ajax usage scenarios.

MUTEX

var mutex = 2;

setTimeout(function() {
 callback();
}, 800);

setTimeout(function() {
 callback();
}, 500);

function callback() {
 if (--mutex === 0) {
  //run code
 }
}

DEFERRED

function timeout(x) {
 var dfd = jQuery.Deferred();
 setTimeout(function() {
  dfd.resolve();
 }, x);
 return dfd.promise();
}

jQuery.when(
timeout(800), timeout(500)).done(function() {
 // run code
});

When using a Deferred as a mutex only, watch out for performance impacts (http://jsperf.com/deferred-vs-mutex/2). Though the convenience, as well as additional benefits supplied by a Deferred is well worth it, and in actual (user driven event based) usage the performance impact should not be noticeable.

Windows equivalent of 'touch' (i.e. the node.js way to create an index.html)

Easy, example with txt file

echo $null >> filename.txt

How can I convert a dictionary into a list of tuples?

>>> d = { 'a': 1, 'b': 2, 'c': 3 }
>>> d.items()
[('a', 1), ('c', 3), ('b', 2)]
>>> [(v, k) for k, v in d.iteritems()]
[(1, 'a'), (3, 'c'), (2, 'b')]

It's not in the order you want, but dicts don't have any specific order anyway.1 Sort it or organize it as necessary.

See: items(), iteritems()


In Python 3.x, you would not use iteritems (which no longer exists), but instead use items, which now returns a "view" into the dictionary items. See the What's New document for Python 3.0, and the new documentation on views.

1: Insertion-order preservation for dicts was added in Python 3.7

Convert an integer to a byte array

What's wrong with converting it to a string?

[]byte(fmt.Sprintf("%d", myint))

How to keep an iPhone app running on background fully operational

From ioS 7 onwards, there are newer ways for apps to run in background. Apple now recognizes that apps have to constantly download and process data constantly.

Here is the new list of all the apps which can run in background.

  1. Apps that play audible content to the user while in the background, such as a music player app
  2. Apps that record audio content while in the background.
  3. Apps that keep users informed of their location at all times, such as a navigation app
  4. Apps that support Voice over Internet Protocol (VoIP)
  5. Apps that need to download and process new content regularly
  6. Apps that receive regular updates from external accessories

You can declare app's supported background tasks in Info.plist using X Code 5+. For eg. adding UIBackgroundModes key to your app’s Info.plist file and adding a value of 'fetch' to the array allows your app to regularly download and processes small amounts of content from the network. You can do the same in the 'capabilities' tab of Application properties in XCode 5 (attaching a snapshot)

Capabilities tab in XCode 5 You can find more about this in Apple documentation

New xampp security concept: Access Forbidden Error 403 - Windows 7 - phpMyAdmin

G:\xampp\apache\conf\extra\httpd-vhosts.conf

#start block
NameVirtualHost *:80

<VirtualHost *:80>
   ServerName localhost
   #change your directory name
   DocumentRoot "G:\xampp\htdocs"
</VirtualHost>

#Your vertual Host
<VirtualHost *:80>
    DocumentRoot "G:/xampp/htdocs/dev2018/guessbook"
    ServerName dev.foreign-recruitment
    <Directory "G:/xampp/htdocs/dev2018/guessbook/">

    </Directory>
</VirtualHost>
#end block

Chaining Observables in RxJS

About promise composition vs. Rxjs, as this is a frequently asked question, you can refer to a number of previously asked questions on SO, among which :

Basically, flatMap is the equivalent of Promise.then.

For your second question, do you want to replay values already emitted, or do you want to process new values as they arrive? In the first case, check the publishReplay operator. In the second case, standard subscription is enough. However you might need to be aware of the cold. vs. hot dichotomy depending on your source (cf. Hot and Cold observables : are there 'hot' and 'cold' operators? for an illustrated explanation of the concept)

Android Facebook style slide

With android support package revision 13( may 2013), there is DrawerLayout for creating a Navigation Drawer that can be pulled in from the edge of a window. And, navigation drawer is a design pattern now.

v4 support library

navigation drawer design pattern

Determining 32 vs 64 bit in C++

"Compiled in 64 bit" is not well defined in C++.

C++ sets only lower limits for sizes such as int, long and void *. There is no guarantee that int is 64 bit even when compiled for a 64 bit platform. The model allows for e.g. 23 bit ints and sizeof(int *) != sizeof(char *)

There are different programming models for 64 bit platforms.

Your best bet is a platform specific test. Your second best, portable decision must be more specific in what is 64 bit.

How to pass variable number of arguments to printf/sprintf

You are looking for variadic functions. printf() and sprintf() are variadic functions - they can accept a variable number of arguments.

This entails basically these steps:

  1. The first parameter must give some indication of the number of parameters that follow. So in printf(), the "format" parameter gives this indication - if you have 5 format specifiers, then it will look for 5 more arguments (for a total of 6 arguments.) The first argument could be an integer (eg "myfunction(3, a, b, c)" where "3" signifies "3 arguments)

  2. Then loop through and retrieve each successive argument, using the va_start() etc. functions.

There are plenty of tutorials on how to do this - good luck!

How do I set the focus to the first input element in an HTML form independent from the id?

Putting this code at the end of your body tag will focus the first visible, non-hidden enabled element on the screen automatically. It will handle most cases I can come up with on short notice.

<script>
    (function(){
        var forms = document.forms || [];
        for(var i = 0; i < forms.length; i++){
            for(var j = 0; j < forms[i].length; j++){
                if(!forms[i][j].readonly != undefined && forms[i][j].type != "hidden" && forms[i][j].disabled != true && forms[i][j].style.display != 'none'){
                    forms[i][j].focus();
                    return;
                }
            }
        }
    })();
</script>

Using Alert in Response.Write Function in ASP.NET

You can simply write

try
 {
    //Your Logic and code
 }
 catch (Exception ex)
 {
    //Error message in  alert box
    Response.Write("<script>alert('Error :" +ex.Message+"');</script>");
 }

it will work fine

How to sort by Date with DataTables jquery plugin?

I got solution after working whole day on it. It is little hacky solution Added span inside td tag

<td><span><%= item.StartICDate %></span></td>. 

Date format which Im using is dd/MM/YYYY. Tested in Datatables1.9.0

How do you format code in Visual Studio Code (VSCode)

While changing the default behavior for Visual Studio Code requires an extension, you may override the default behavior in the workspace or user level. It works for most of the supported languages (I can guarantee HTML, JavaScript, and C#).

Workspace level

Benefits

  • Does not require an extension
  • Can be shared among teams

Outcomes

  • .vscode/settings.json is created in the project root folder

How To?

  1. Go to: Menu FilePreferencesWorkspace Settings

  2. Add and save "editor.formatOnType": true to settings.json (which overrides default behavior for the project you work on by creating .vscode/settings.json file).

    How it looks

User environment level

Benefits

  • Does not requires extension
  • Personal development environment tweeking to rule them all (settings:))

Outcomes

  • User's settings.json is modified (see location by operating system below)

How To?

  1. Go to: menu FilePreferencesUser Settings

  2. Add or change the value of "editor.formatOnType": false to "editor.formatOnType": true in the user settings.json

Your Visual Studio Code user's settings.json location is:

Settings file locations depending on your platform, the user settings file is located here:

  • Windows: %APPDATA%\Code\User\settings.json
  • Mac: $HOME/Library/Application Support/Code/User/settings.json
  • Linux: $HOME/.config/Code/User/settings.json The workspace setting file is located under the .vscode folder in your project.

More details may be found here.

Click event doesn't work on dynamically generated elements

The click() binding you're using is called a "direct" binding which will only attach the handler to elements that already exist. It won't get bound to elements created in the future. To do that, you'll have to create a "delegated" binding by using on().

Delegated events have the advantage that they can process events from descendant elements that are added to the document at a later time.

Source

Here's what you're looking for:

_x000D_
_x000D_
var counter = 0;_x000D_
_x000D_
$("button").click(function() {_x000D_
    $("h2").append("<p class='test'>click me " + (++counter) + "</p>")_x000D_
});_x000D_
_x000D_
// With on():_x000D_
_x000D_
$("h2").on("click", "p.test", function(){_x000D_
    alert($(this).text());_x000D_
});
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>_x000D_
<h2></h2>_x000D_
<button>generate new element</button>
_x000D_
_x000D_
_x000D_

The above works for those using jQuery version 1.7+. If you're using an older version, refer to the previous answer below.


Previous Answer:

Try using live():

$("button").click(function(){
    $("h2").html("<p class='test'>click me</p>")
});   


$(".test").live('click', function(){
    alert('you clicked me!');
});

Worked for me. Tried it with jsFiddle.

Or there's a new-fangled way of doing it with delegate():

$("h2").delegate("p", "click", function(){
    alert('you clicked me again!');
});

An updated jsFiddle.

Batch command to move files to a new directory

Something like this might help:

SET Today=%Date:~10,4%%Date:~4,2%%Date:~7,2%
mkdir C:\Test\Backup-%Today%
move C:\Test\Log\*.* C:\Test\Backup-%Today%\
SET Today=

The important part is the first line. It takes the output of the internal DATE value and parses it into an environmental variable named Today, in the format CCYYMMDD, as in '20110407`.

The %Date:~10,4% says to extract a *substring of the Date environmental variable 'Thu 04/07/2011' (built in - type echo %Date% at a command prompt) starting at position 10 for 4 characters (2011). It then concatenates another substring of Date: starting at position 4 for 2 chars (04), and then concats two additional characters starting at position 7 (07).

*The substring value starting points are 0-based.

You may need to adjust these values depending on the date format in your locale, but this should give you a starting point.

What tools do you use to test your public REST API?

Postman in the chrome store is simple but powerful.

Writing a new line to file in PHP (line feed)

Use PHP_EOL which outputs \r\n or \n depending on the OS.

how to convert image to byte array in java?

Here is a complete version of code for doing this. I have tested it. The BufferedImage and Base64 class do the trick mainly. Also some parameter needs to be set correctly.

public class SimpleConvertImage {
    public static void main(String[] args) throws IOException{
        String dirName="C:\\";
        ByteArrayOutputStream baos=new ByteArrayOutputStream(1000);
        BufferedImage img=ImageIO.read(new File(dirName,"rose.jpg"));
        ImageIO.write(img, "jpg", baos);
        baos.flush();

        String base64String=Base64.encode(baos.toByteArray());
        baos.close();

        byte[] bytearray = Base64.decode(base64String);

        BufferedImage imag=ImageIO.read(new ByteArrayInputStream(bytearray));
        ImageIO.write(imag, "jpg", new File(dirName,"snap.jpg"));
    }
}

Reference link

How to check if iframe is loaded or it has a content?

You can use the iframe's load event to respond when the iframe loads.

document.querySelector('iframe').onload = function(){
    console.log('iframe loaded');
};

This won't tell you whether the correct content loaded: To check that, you can inspect the contentDocument.

document.querySelector('iframe').onload = function(){
    var iframeBody = this.contentDocument.body;
    console.log('iframe loaded, body is: ', body);
};

Checking the contentDocument won't work if the iframe src points to a different domain from where your code is running.

Calculating Time Difference

from time import time

start_time = time()
...

end_time = time()
seconds_elapsed = end_time - start_time

hours, rest = divmod(seconds_elapsed, 3600)
minutes, seconds = divmod(rest, 60)

MySQL: How to add one day to datetime field in query

You can use the DATE_ADD() function:

... WHERE DATE(DATE_ADD(eventdate, INTERVAL -1 DAY)) = CURRENT_DATE

It can also be used in the SELECT statement:

SELECT DATE_ADD('2010-05-11', INTERVAL 1 DAY) AS Tomorrow;
+------------+
| Tomorrow   |
+------------+
| 2010-05-12 |
+------------+
1 row in set (0.00 sec)

How to verify a Text present in the loaded page through WebDriver

Yes, you can do that which returns boolean. The following java code in WebDriver with TestNG or JUnit can do:

protected boolean isTextPresent(String text){
    try{
        boolean b = driver.getPageSource().contains(text);
        return b;
    }
    catch(Exception e){
        return false;
    }
  }

Now call the above method as below:

assertTrue(isTextPresent("Your text"));

Or, there is another way. I think, this is the better way:

private StringBuffer verificationErrors = new StringBuffer();
try {
                  assertTrue(driver.findElement(By.cssSelector("BODY")).getText().matches("^[\\s\\S]*    Your text here\r\n\r\n[\\s\\S]*$"));
  } catch (Error e) {
     verificationErrors.append(e.toString());
   }

How to set value to variable using 'execute' in t-sql?

You can use output parameters with sp_executesql.

DECLARE @dbName nvarchar(128) = 'myDb'
DECLARE @siteId int 
DECLARE @SQL nvarchar(max) = N'SELECT TOP 1 @siteId = Id FROM ' + quotename(@dbName) + N'..myTbl'
exec sp_executesql @SQL, N'@siteId int out', @siteId out
select @siteId

How to change letter spacing in a Textview?

More space:

  android:letterSpacing="0.1"

Less space:

 android:letterSpacing="-0.07"

How do I format date value as yyyy-mm-dd using SSIS expression builder?

Looks like you created a separate question. I was answering your other question How to change flat file source using foreach loop container in an SSIS package? with the same answer. Anyway, here it is again.

Create two string data type variables namely DirPath and FilePath. Set the value C:\backup\ to the variable DirPath. Do not set any value to the variable FilePath.

Variables

Select the variable FilePath and select F4 to view the properties. Set the EvaluateAsExpression property to True and set the Expression property as @[User::DirPath] + "Source" + (DT_STR, 4, 1252) DATEPART("yy" , GETDATE()) + "-" + RIGHT("0" + (DT_STR, 2, 1252) DATEPART("mm" , GETDATE()), 2) + "-" + RIGHT("0" + (DT_STR, 2, 1252) DATEPART("dd" , GETDATE()), 2)

Expression

Call of overloaded function is ambiguous

The solution is very simple if we consider the type of the constant value, which should be "unsigned int" instead of "int".

Instead of:

setval(0)

Use:

setval(0u)

The suffix "u" tell the compiler this is a unsigned integer. Then, no conversion would be needed, and the call will be unambiguous.

Return list using select new in LINQ

Method can not return anonymous type. It has to be same as the type defined in method return type. Check the signature of GetProjectForCombo and see what return type you have specified.

Create a class ProjectInfo with required properties and then in new expression create object of ProjectInfo type.

class ProjectInfo
{
   public string Name {get; set; }
   public long Id {get; set; }
}

public List<ProjectInfo> GetProjectForCombo()
{
    using (MyDataContext db = new MyDataContext (DBHelper.GetConnectionString()))
    {
        var query = from pro in db.Projects
                    select new ProjectInfo(){ Name = pro.ProjectName, Id = pro.ProjectId };

        return query.ToList();
    }
}

Create timestamp variable in bash script

You can use

timestamp=`date --rfc-3339=seconds`

This delivers in the format 2014-02-01 15:12:35-05:00

The back-tick (`) characters will cause what is between them to be evaluated and have the result included in the line. date --help has other options.

How do I create a multiline Python string with inline variables?

A dictionary can be passed to format(), each key name will become a variable for each associated value.

dict = {'string1': 'go',
        'string2': 'now',
        'string3': 'great'}

multiline_string = '''I'm will {string1} there
I will go {string2}
{string3}'''.format(**dict)

print(multiline_string)


Also a list can be passed to format(), the index number of each value will be used as variables in this case.

list = ['go',
        'now',
        'great']

multiline_string = '''I'm will {0} there
I will go {1}
{2}'''.format(*list)

print(multiline_string)


Both solutions above will output the same:

I'm will go there
I will go now
great

Angularjs prevent form submission when input validation fails

Although not a direct solution for the OPs question, if your form is within an ng-app context, but you want Angular to ignore it altogether, you can do this explicitly using the ngNonBindable directive:

<form ng-non-bindable>
  ...
</form>

Using Jquery AJAX function with datatype HTML

Here is a version that uses dataType html, but this is far less explicit, because i am returning an empty string to indicate an error.

Ajax call:

$.ajax({
  type : 'POST',
  url : 'post.php',
  dataType : 'html',
  data: {
      email : $('#email').val()
  },
  success : function(data){
      $('#waiting').hide(500);
      $('#message').removeClass().addClass((data == '') ? 'error' : 'success')
     .html(data).show(500);
      if (data == '') {
          $('#message').html("Format your email correcly");
          $('#demoForm').show(500);
      }
  },
  error : function(XMLHttpRequest, textStatus, errorThrown) {
      $('#waiting').hide(500);
      $('#message').removeClass().addClass('error')
      .text('There was an error.').show(500);
      $('#demoForm').show(500);
  }

});

post.php

<?php
sleep(1);

function processEmail($email) {
    if (preg_match("#^[a-zA-Z0-9_.-]+@[a-zA-Z0-9-]+.[a-zA-Z0-9-.]+$#", $email)) {
        // your logic here (ex: add into database)
        return true;
    }
    return false;
}

if (processEmail($_POST['email'])) {
    echo "<span>Your email is <strong>{$_POST['email']}</strong></span>";
}

Can I add and remove elements of enumeration at runtime in Java

You can load a Java class from source at runtime. (Using JCI, BeanShell or JavaCompiler)

This would allow you to change the Enum values as you wish.

Note: this wouldn't change any classes which referred to these enums so this might not be very useful in reality.

How to export a CSV to Excel using Powershell

Why would you bother? Load your CSV into Excel like this:

$csv = Join-Path $env:TEMP "process.csv"
$xls = Join-Path $env:TEMP "process.xlsx"

$xl = New-Object -COM "Excel.Application"
$xl.Visible = $true

$wb = $xl.Workbooks.OpenText($csv)

$wb.SaveAs($xls, 51)

You just need to make sure that the CSV export uses the delimiter defined in your regional settings. Override with -Delimiter if need be.


Edit: A more general solution that should preserve the values from the CSV as plain text. Code for iterating over the CSV columns taken from here.

$csv = Join-Path $env:TEMP "input.csv"
$xls = Join-Path $env:TEMP "output.xlsx"

$xl = New-Object -COM "Excel.Application"
$xl.Visible = $true

$wb = $xl.Workbooks.Add()
$ws = $wb.Sheets.Item(1)

$ws.Cells.NumberFormat = "@"

$i = 1
Import-Csv $csv | ForEach-Object {
  $j = 1
  foreach ($prop in $_.PSObject.Properties) {
    if ($i -eq 1) {
      $ws.Cells.Item($i, $j++).Value = $prop.Name
    } else {
      $ws.Cells.Item($i, $j++).Value = $prop.Value
    }
  }
  $i++
}

$wb.SaveAs($xls, 51)
$wb.Close()

$xl.Quit()
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($xl)

Obviously this second approach won't perform too well, because it's processing each cell individually.

No 'Access-Control-Allow-Origin' header is present on the requested resource - Resteasy

Seems your resource POSTmethod won't get hit as @peeskillet mention. Most probably your ~POST~ request won't work, because it may not be a simple request. The only simple requests are GET, HEAD or POST and request headers are simple(The only simple headers are Accept, Accept-Language, Content-Language, Content-Type= application/x-www-form-urlencoded, multipart/form-data, text/plain).

Since in you already add Access-Control-Allow-Origin headers to your Response, you can add new OPTIONS method to your resource class.

    @OPTIONS
@Path("{path : .*}")
public Response options() {
    return Response.ok("")
            .header("Access-Control-Allow-Origin", "*")
            .header("Access-Control-Allow-Headers", "origin, content-type, accept, authorization")
            .header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS, HEAD")
            .header("Access-Control-Max-Age", "2000")
            .build();
}

How to copy Docker images from one host to another without using a repository

All other answers are very helpful. I just went through the same problem and figure out an easy way with docker machine scp.

Since Docker Machine v0.3.0, scp was introduced to copy files from one Docker machine to another. This is very convenient if you want copying a file from your local computer to a remote Docker machine such as AWS EC2 or Digital Ocean because Docker Machine is taking care of SSH credentials for you.

  1. Save you images using docker save like:

    docker save -o docker-images.tar app-web
    
  2. Copy images using docker-machine scp

    docker-machine scp ./docker-images.tar remote-machine:/home/ubuntu
    

Assume your remote Docker machine is remote-machine and the directory you want the tar file to be is /home/ubuntu.

  1. Load the Docker image

    docker-machine ssh remote-machine sudo docker load -i docker-images.tar
    

How to support UTF-8 encoding in Eclipse

Open Eclipse and do the following steps:

  1. Window -> Preferences -> Expand General and click Workspace, text file encoding (near bottom) has an encoding chooser.
  2. Select "Other" radio button -> Select UTF-8 from the drop down
  3. Click Apply and OK button OR click simply OK button

enter image description here

How can I reload .emacs after changing it?

Here is a quick and easy way to quick test your config. You can also use C-x C-e at the end of specific lisp to execute certain function individually.

C-x C-e runs the command eval-last-sexp (found in global-map), which is an interactive compiled Lisp function.

It is bound to C-x C-e.

(eval-last-sexp EVAL-LAST-SEXP-ARG-INTERNAL)

Evaluate sexp before point; print value in the echo area. Interactively, with prefix argument, print output into current buffer.

Normally, this function truncates long output according to the value of the variables ‘eval-expression-print-length’ and ‘eval-expression-print-level’. With a prefix argument of zero, however, there is no such truncation. Such a prefix argument also causes integers to be printed in several additional formats (octal, hexadecimal, and character).

If ‘eval-expression-debug-on-error’ is non-nil, which is the default, this command arranges for all errors to enter the debugger.

Foreach Control in form, how can I do something to all the TextBoxes in my Form?

If you are using C# 3.0 or higher you can do the following

foreach ( TextBox tb in this.Controls.OfType<TextBox>()) {
  ..
}

Without C# 3.0 you can do the following

foreach ( Control c in this.Controls ) {
  TextBox tb = c as TextBox;
  if ( null != tb ) {
    ...
  }
}

Or even better, write OfType in C# 2.0.

public static IEnumerable<T> OfType<T>(IEnumerable e) where T : class { 
  foreach ( object cur in e ) {
    T val = cur as T;
    if ( val != null ) {
      yield return val;
    }
  }
}

foreach ( TextBox tb in OfType<TextBox>(this.Controls)) {
  ..
}

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

You can manually place a check in your code. Like this -


    if result != []:
        for face in result:
            bounding_box = face['box']
            x, y, w, h = bounding_box[0], bounding_box[1], bounding_box[2], bounding_box[3]
            rect_face = cv2.rectangle(frame, (x, y), (x+w, y+h), (46, 204, 113), 2)
            face = rgb[y:y+h, x:x+w]

            #CHECK FACE SIZE (EXIST OR NOT)
            if face.shape[0]*face.shape[1] > 0:

                predicted_name, class_probability = face_recognition(face)

                print("Result: ", predicted_name, class_probability)
`

"The following SDK components were not installed: sys-img-x86-addon-google_apis-google-22 and addon-google_apis-google-22"

I am having the same issue when trying to upgrade Android Studio from 1.1 to 1.2 on Mac OS 10.10. I solved the problem by selecting custom installation instead of standard. Also we need to select the Android SDK Platform (Lollipop 5.1).

Can there be an apostrophe in an email address?

Yes, according to RFC 3696 apostrophes are valid as long as they come before the @ symbol.

How can a Java program get its own process ID?

I know this is an old thread, but I wanted to call out that API for getting the PID (as well as other manipulation of the Java process at runtime) is being added to the Process class in JDK 9: http://openjdk.java.net/jeps/102

how to convert binary string to decimal?

I gathered all what others have suggested and created following function which has 3 arguments, the number and the base which that number has come from and the base which that number is going to be on:

changeBase(1101000, 2, 10) => 104

Run Code Snippet to try it yourself:

_x000D_
_x000D_
function changeBase(number, fromBase, toBase) {_x000D_
                        if (fromBase == 10)_x000D_
                            return (parseInt(number)).toString(toBase)_x000D_
                        else if (toBase == 10)_x000D_
                            return parseInt(number, fromBase);_x000D_
                        else{_x000D_
                            var numberInDecimal = parseInt(number, fromBase);_x000D_
                            return (parseInt(numberInDecimal)).toString(toBase);_x000D_
                    }_x000D_
}_x000D_
_x000D_
$("#btnConvert").click(function(){_x000D_
  var number = $("#txtNumber").val(),_x000D_
  fromBase = $("#txtFromBase").val(),_x000D_
  toBase = $("#txtToBase").val();_x000D_
  $("#lblResult").text(changeBase(number, fromBase, toBase));_x000D_
});
_x000D_
#lblResult{_x000D_
  padding: 20px;_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<input id="txtNumber" type="text" placeholder="Number" />_x000D_
<input id="txtFromBase" type="text" placeholder="From Base" />_x000D_
<input id="txtToBase" type="text" placeholder="To Base" />_x000D_
<input id="btnConvert" type="button" value="Convert" />_x000D_
<span id="lblResult"></span>_x000D_
_x000D_
<p>Hint: <br />_x000D_
Try 110, 2, 10 and it will return 6; (110)<sub>2</sub> = 6<br />_x000D_
_x000D_
or 2d, 16, 10 => 45 meaning: (2d)<sub>16</sub> = 45<br />_x000D_
or 45, 10, 16 => 2d meaning: 45 = (2d)<sub>16</sub><br />_x000D_
or 2d, 2, 16 => 2d meaning: (101101)<sub>2</sub> = (2d)<sub>16</sub><br />_x000D_
</p>
_x000D_
_x000D_
_x000D_

FYI: If you want to pass 2d as hex number, you need to send it as a string so it goes like this: changeBase('2d', 16, 10)

In python, how do I cast a class object to a dict

There is no magic method that will do what you want. The answer is simply name it appropriately. asdict is a reasonable choice for a plain conversion to dict, inspired primarily by namedtuple. However, your method will obviously contain special logic that might not be immediately obvious from that name; you are returning only a subset of the class' state. If you can come up with with a slightly more verbose name that communicates the concepts clearly, all the better.

Other answers suggest using __iter__, but unless your object is truly iterable (represents a series of elements), this really makes little sense and constitutes an awkward abuse of the method. The fact that you want to filter out some of the class' state makes this approach even more dubious.

Excel VBA App stops spontaneously with message "Code execution has been halted"

I have had this problem also using excel 2007 with a foobar.xlsm (macro enabled ) workbook which would get the "Code execution has been interrupted" by simply trying to close the workbook on the red X in the right corner with no macros running at all, or any "initialize" form, workbook, or workheet macros either. The options I got were "End" or "Continue", Debug was always greyed out. I did as a previous poster suggested Control Panel->Programs and Features-> right click "Microsoft Office Proffesional 2007" (in my case) ->change->repair.

This resolved the problem for me. I might add this happened soon after a MS update and I also found an addin in Excel called "Team Foundation" from Microsoft which I certainly didnt install voluntarily

javax.websocket client simple example

TooTallNate has a simple client side https://github.com/TooTallNate/Java-WebSocket

Just add the java_websocket.jar in the dist folder into your project.

 import org.java_websocket.client.WebSocketClient;
 import org.java_websocket.drafts.Draft_10;
 import org.java_websocket.handshake.ServerHandshake;
 import org.json.JSONException;
 import org.json.JSONObject;

  WebSocketClient mWs = new WebSocketClient( new URI( "ws://socket.example.com:1234" ), new Draft_10() )
{
                    @Override
                    public void onMessage( String message ) {
                     JSONObject obj = new JSONObject(message);
                     String channel = obj.getString("channel");
                    }

                    @Override
                    public void onOpen( ServerHandshake handshake ) {
                        System.out.println( "opened connection" );
                    }

                    @Override
                    public void onClose( int code, String reason, boolean remote ) {
                        System.out.println( "closed connection" );
                    }

                    @Override
                    public void onError( Exception ex ) {
                        ex.printStackTrace();
                    }

                };
 //open websocket
 mWs.connect();
 JSONObject obj = new JSONObject();
 obj.put("event", "addChannel");
 obj.put("channel", "ok_btccny_ticker");
 String message = obj.toString();
 //send message
 mWs.send(message);

// and to close websocket

 mWs.close();

How to dynamically set bootstrap-datepicker's date value?

Please note that if you initiate a datepicker with a custom format, you can pass the simple string date as the second argument. This saves a few lines.

$('.selector').datepicker({
    format:'dd/mm/yyyy',
});

$('.selector').datepicker('update', '13/09/2019');

Still getting warning : Configuration 'compile' is obsolete and has been replaced with 'implementation'

I have tried changing the google gms services to the latest com.google.gms:google-services:3.2.1 in Android Studio 3.0.1 but the warning still persists.

As recommended by the compiler,I changed all compile dependencies to implementation and testCompile to testImplementation like this..

dependencies {
implementation fileTree(include: ['*.jar'], dir: 'libs')
implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support:mediarouter-v7:27.1.1'
implementation 'com.android.support:design:27.1.1'
implementation 'com.google.firebase:firebase-ads:12.0.1'
implementation 'com.google.firebase:firebase-crash:12.0.1'
implementation 'com.google.firebase:firebase-core:12.0.1'
implementation 'com.google.firebase:firebase-messaging:12.0.1'
implementation 'com.google.firebase:firebase-perf:12.0.1'
implementation 'com.google.firebase:firebase-appindexing:12.0.1'
implementation 'com.android.support.constraint:constraint-layout:1.0.2'
testImplementation 'junit:junit:4.12'
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}

And finally the warning is removed!

Using the RUN instruction in a Dockerfile with 'source' does not work

According to Docker documentation

To use a different shell, other than ‘/bin/sh’, use the exec form passing in the desired shell. For example,

RUN ["/bin/bash", "-c", "echo hello"]

See https://docs.docker.com/engine/reference/builder/#run

How to get status code from webclient?

You can check if the error is of type WebException and then inspect the response code;

if (e.Error.GetType().Name == "WebException")
{
   WebException we = (WebException)e.Error;
   HttpWebResponse response = (System.Net.HttpWebResponse)we.Response;
   if (response.StatusCode==HttpStatusCode.NotFound)
      System.Diagnostics.Debug.WriteLine("Not found!");
}

or

try
{
    // send request
}
catch (WebException e)
{
    // check e.Status as above etc..
}

Angular2 - Input Field To Accept Only Numbers

Use pattern attribute for input like below:

<input type="text" pattern="[0-9]+" >

Python datetime to string without microsecond component

Yet another option:

>>> import time
>>> time.strftime("%Y-%m-%d %H:%M:%S")
'2011-11-03 11:31:28'

By default this uses local time, if you need UTC you can use the following:

>>> time.strftime("%Y-%m-%d %H:%M:%S", time.gmtime())
'2011-11-03 18:32:20'

iPhone UITextField - Change placeholder text color

Overriding drawPlaceholderInRect: would be the correct way, but it does not work due to a bug in the API (or the documentation).

The method never gets called on an UITextField.

See also drawTextInRect on UITextField not called

You might use digdog's solution. As I am not sure if that gets past Apples review, I chose a different solution: Overlay the text field with my own label which imitates the placeholder behaviour.

This is a bit messy though. The code looks like this (Note I am doing this inside a subclass of TextField):

@implementation PlaceholderChangingTextField

- (void) changePlaceholderColor:(UIColor*)color
{    
    // Need to place the overlay placeholder exactly above the original placeholder
    UILabel *overlayPlaceholderLabel = [[[UILabel alloc] initWithFrame:CGRectMake(self.frame.origin.x + 8, self.frame.origin.y + 4, self.frame.size.width - 16, self.frame.size.height - 8)] autorelease];
    overlayPlaceholderLabel.backgroundColor = [UIColor whiteColor];
    overlayPlaceholderLabel.opaque = YES;
    overlayPlaceholderLabel.text = self.placeholder;
    overlayPlaceholderLabel.textColor = color;
    overlayPlaceholderLabel.font = self.font;
    // Need to add it to the superview, as otherwise we cannot overlay the buildin text label.
    [self.superview addSubview:overlayPlaceholderLabel];
    self.placeholder = nil;
}

Checking if date is weekend PHP

Another way is to use the DateTime class, this way you can also specify the timezone. Note: PHP 5.3 or higher.

// For the current date
function isTodayWeekend() {
    $currentDate = new DateTime("now", new DateTimeZone("Europe/Amsterdam"));
    return $currentDate->format('N') >= 6;
}

If you need to be able to check a certain date string, you can use DateTime::createFromFormat

function isWeekend($date) {
    $inputDate = DateTime::createFromFormat("d-m-Y", $date, new DateTimeZone("Europe/Amsterdam"));
    return $inputDate->format('N') >= 6;
}

The beauty of this way is that you can specify the timezone without changing the timezone globally in PHP, which might cause side-effects in other scripts (for ex. Wordpress).

Float and double datatype in Java

The Wikipedia page on it is a good place to start.

To sum up:

  • float is represented in 32 bits, with 1 sign bit, 8 bits of exponent, and 23 bits of the significand (or what follows from a scientific-notation number: 2.33728*1012; 33728 is the significand).

  • double is represented in 64 bits, with 1 sign bit, 11 bits of exponent, and 52 bits of significand.

By default, Java uses double to represent its floating-point numerals (so a literal 3.14 is typed double). It's also the data type that will give you a much larger number range, so I would strongly encourage its use over float.

There may be certain libraries that actually force your usage of float, but in general - unless you can guarantee that your result will be small enough to fit in float's prescribed range, then it's best to opt with double.

If you require accuracy - for instance, you can't have a decimal value that is inaccurate (like 1/10 + 2/10), or you're doing anything with currency (for example, representing $10.33 in the system), then use a BigDecimal, which can support an arbitrary amount of precision and handle situations like that elegantly.

JQuery - $ is not defined

Are you using any other JavaScript libraries? If so, you will probably need to use jQuery in compatibility mode:

http://docs.jquery.com/Using_jQuery_with_Other_Libraries

What algorithms compute directions from point A to point B on a map?

Here's the world's fastest routing algorithms compared and proven for correctness:

http://algo2.iti.uka.de/schultes/hwy/schultes_diss.pdf

Here's a google tech talk on the subject:

http://www.youtube.com/watch?v=-0ErpE8tQbw

Here's a implementation of the highway-hierarchies algorithm as discussed by schultes (currently in berlin only, I'm writing the interface and a mobile version is being developed as well):

http://tom.mapsforge.org/

Creating a selector from a method name with parameters

Beyond what's been said already about selectors, you may want to look at the NSInvocation class.

An NSInvocation is an Objective-C message rendered static, that is, it is an action turned into an object. NSInvocation objects are used to store and forward messages between objects and between applications, primarily by NSTimer objects and the distributed objects system.

An NSInvocation object contains all the elements of an Objective-C message: a target, a selector, arguments, and the return value. Each of these elements can be set directly, and the return value is set automatically when the NSInvocation object is dispatched.

Keep in mind that while it's useful in certain situations, you don't use NSInvocation in a normal day of coding. If you're just trying to get two objects to talk to each other, consider defining an informal or formal delegate protocol, or passing a selector and target object as has already been mentioned.

When to use malloc for char pointers

As was indicated by others, you don't need to use malloc just to do:

const char *foo = "bar";

The reason for that is exactly that *foo is a pointer — when you initialize foo you're not creating a copy of the string, just a pointer to where "bar" lives in the data section of your executable. You can copy that pointer as often as you'd like, but remember, they're always pointing back to the same single instance of that string.

So when should you use malloc? Normally you use strdup() to copy a string, which handles the malloc in the background. e.g.

const char *foo = "bar";
char *bar = strdup(foo); /* now contains a new copy of "bar" */
printf("%s\n", bar);     /* prints "bar" */
free(bar);               /* frees memory created by strdup */

Now, we finally get around to a case where you may want to malloc if you're using sprintf() or, more safely snprintf() which creates / formats a new string.

char *foo = malloc(sizeof(char) * 1024);        /* buffer for 1024 chars */
snprintf(foo, 1024, "%s - %s\n", "foo", "bar"); /* puts "foo - bar\n" in foo */
printf(foo);                                    /* prints "foo - bar" */
free(foo);                                      /* frees mem from malloc */

I'm getting favicon.ico error

In Angular earlier we had .angular-cli.json file which referred to favicon.ico. If you'll upgrade into one of the newer versions of Angular then you'll have angular.json instead. For these newer versions, you have to refer the favicon path in your index.html from now onwards.

PHP Get name of current directory

Actually I found the best solution is the following:

$cur_dir = explode('\\', getcwd());
echo $cur_dir[count($cur_dir)-1];

if your dir is www\var\path\ Current_Path

then this returns Current_path

Extracting specific selected columns to new DataFrame as a copy

There is a way of doing this and it actually looks similar to R

new = old[['A', 'C', 'D']].copy()

Here you are just selecting the columns you want from the original data frame and creating a variable for those. If you want to modify the new dataframe at all you'll probably want to use .copy() to avoid a SettingWithCopyWarning.

An alternative method is to use filter which will create a copy by default:

new = old.filter(['A','B','D'], axis=1)

Finally, depending on the number of columns in your original dataframe, it might be more succinct to express this using a drop (this will also create a copy by default):

new = old.drop('B', axis=1)

Set value for particular cell in pandas DataFrame with iloc

Another way is to get the row index and then use df.loc or df.at.

# get row index 'label' from row number 'irow'
label = df.index.values[irow] 
df.at[label, 'COL_NAME'] = x

WebDriver - wait for element using Java

You can use Explicit wait or Fluent Wait

Example of Explicit Wait -

WebDriverWait wait = new WebDriverWait(WebDriverRefrence,20);
WebElement aboutMe;
aboutMe= wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("about_me")));     

Example of Fluent Wait -

Wait<WebDriver> wait = new FluentWait<WebDriver>(driver)                            
.withTimeout(20, TimeUnit.SECONDS)          
.pollingEvery(5, TimeUnit.SECONDS)          
.ignoring(NoSuchElementException.class);    

  WebElement aboutMe= wait.until(new Function<WebDriver, WebElement>() {       
public WebElement apply(WebDriver driver) { 
return driver.findElement(By.id("about_me"));     
 }  
});  

Check this TUTORIAL for more details.

How do you automatically resize columns in a DataGridView control AND allow the user to resize the columns on that same grid?

Did you try to set up the FillWeight property of your DataGridViewColumns object?

For example:

this.grid1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;
this.grid1.Columns[0].FillWeight = 1.5;

I think it should work in your case.

Exception : AAPT2 error: check logs for details

If you are getting this error only when you are generating signed Apk . Then the problem might be in one or more of the imported media file format. I have used an image directly from net to studio and was not able to generate sign apk, then found the error .

from Gradle >assembleRelease then got the error in console. see the error log in console image. This was my Error, See its clearly written that one of my image format is not valid or unknown

Swift - How to convert String to Double

Try this:

   var myDouble = myString.bridgeToObjectiveC().doubleValue
   println(myDouble)

NOTE

Removed in Beta 5. This no longer works ?

ERROR in Cannot find module 'node-sass'

One of the cases is the post-install process fails. Right after node-sass is installed, the post-install script will be executed. It requires Python and a C++ builder for that process. The log 'gyp: No Xcode or CLT version detected!' maybe because it couldn't find any C++ builder. So try installing Python and any C++ builder then put their directories in environment variables so that npm can find them. (I come from Windows)

How do I count unique visitors to my site?

Here is a nice tutorial, it is what you need. (Source: coursesweb.net/php-mysql)

Register and show online users and visitors

Count Online users and visitors using a MySQL table

In this tutorial you can learn how to register, to count, and display in your webpage the number of online users and visitors. The principle is this: each user / visitor is registered in a text file or database. Every time a page of the website is accessed, the php script deletes all records older than a certain time (eg 2 minutes), adds the current user / visitor and takes the number of records left to display.

You can store the online users and visitors in a file on the server, or in a MySQL table. In this case, I think that using a text file to add and read the records is faster than storing them into a MySQL table, which requires more requests.

First it's presented the method with recording in a text file on the server, than the method with MySQL table.

To download the files with the scripts presented in this tutorial, click -> Count Online Users and Visitors.

• Both scripts can be included in ".php" files (with include()), or in ".html" files (with <script>), as you can see in the examples presented at the bottom of this page; but the server must run PHP.

Storing online users and visitors in a text file

To add records in a file on the server with PHP you must set CHMOD 0766 (or CHMOD 0777) permissions to that file, so the PHP can write data in it.

  1. Create a text file on your server (for example, named userson.txt) and give it CHMOD 0777 permissions (in your FTP application, right click on that file, choose Properties, then select Read, Write, and Execute options).
  2. Create a PHP file (named usersontxt.php) having the code below, then copy this php file in the same directory as userson.txt.

The code for usersontxt.php;

<?php
// Script Online Users and Visitors - http://coursesweb.net/php-mysql/
if(!isset($_SESSION)) session_start();        // start Session, if not already started

$filetxt = 'userson.txt';  // the file in which the online users /visitors are stored
$timeon = 120;             // number of secconds to keep a user online
$sep = '^^';               // characters used to separate the user name and date-time
$vst_id = '-vst-';        // an identifier to know that it is a visitor, not logged user

/*
 If you have an user registration script,
 replace $_SESSION['nume'] with the variable in which the user name is stored.
 You can get a free registration script from:  http://coursesweb.net/php-mysql/register-login-script-users-online_s2
*/

// get the user name if it is logged, or the visitors IP (and add the identifier)

    $uvon = isset($_SESSION['nume']) ? $_SESSION['nume'] : $_SERVER['SERVER_ADDR']. $vst_id;

$rgxvst = '/^([0-9\.]*)'. $vst_id. '/i';         // regexp to recognize the line with visitors
$nrvst = 0;                                       // to store the number of visitors

// sets the row with the current user /visitor that must be added in $filetxt (and current timestamp)

    $addrow[] = $uvon. $sep. time();

// check if the file from $filetxt exists and is writable

    if(is_writable($filetxt)) {
      // get into an array the lines added in $filetxt
      $ar_rows = file($filetxt, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
      $nrrows = count($ar_rows);

            // number of rows

  // if there is at least one line, parse the $ar_rows array

      if($nrrows>0) {
        for($i=0; $i<$nrrows; $i++) {
          // get each line and separate the user /visitor and the timestamp
          $ar_line = explode($sep, $ar_rows[$i]);
      // add in $addrow array the records in last $timeon seconds
          if($ar_line[0]!=$uvon && (intval($ar_line[1])+$timeon)>=time()) {
            $addrow[] = $ar_rows[$i];
          }
        }
      }
    }

$nruvon = count($addrow);                   // total online
$usron = '';                                    // to store the name of logged users
// traverse $addrow to get the number of visitors and users
for($i=0; $i<$nruvon; $i++) {
 if(preg_match($rgxvst, $addrow[$i])) $nrvst++;       // increment the visitors
 else {
   // gets and stores the user's name
   $ar_usron = explode($sep, $addrow[$i]);
   $usron .= '<br/> - <i>'. $ar_usron[0]. '</i>';
 }
}
$nrusr = $nruvon - $nrvst;              // gets the users (total - visitors)

// the HTML code with data to be displayed
$reout = '<div id="uvon"><h4>Online: '. $nruvon. '</h4>Visitors: '. $nrvst. '<br/>Users: '. $nrusr. $usron. '</div>';

// write data in $filetxt
if(!file_put_contents($filetxt, implode("\n", $addrow))) $reout = 'Error: Recording file not exists, or is not writable';

// if access from <script>, with GET 'uvon=showon', adds the string to return into a JS statement
// in this way the script can also be included in .html files
if(isset($_GET['uvon']) && $_GET['uvon']=='showon') $reout = "document.write('$reout');";

echo $reout;             // output /display the result
?>
  1. If you want to include the script above in a ".php" file, add the following code in the place you want to show the number of online users and visitors:

4.To show the number of online visitors /users in a ".html" file, use this code:

<script type="text/javascript" src="usersontxt.php?uvon=showon"></script>

This script (and the other presented below) works with $_SESSION. At the beginning of the PHP file in which you use it, you must add: session_start();. Count Online users and visitors using a MySQL table

To register, count and show the number of online visitors and users in a MySQL table, require to perform three SQL queries: Delete the records older than a certain time. Insert a row with the new user /visitor, or, if it is already inserted, Update the timestamp in its column. Select the remaining rows. Here's the code for a script that uses a MySQL table (named "userson") to store and display the Online Users and Visitors.

  1. First we create the "userson" table, with 2 columns (uvon, dt). In the "uvon" column is stored the name of the user (if logged in) or the visitor's IP. In the "dt" column is stored a number with the timestamp (Unix time) when the page is accessed.
  • Add the following code in a php file (for example, named "create_userson.php"):

The code for create_userson.php:

<?php
header('Content-type: text/html; charset=utf-8');

// HERE add your data for connecting to MySQ database
$host = 'localhost';           // MySQL server address
$user = 'root';                // User name
$pass = 'password';            // User`s password
$dbname = 'database';          // Database name

// connect to the MySQL server
$conn = new mysqli($host, $user, $pass, $dbname);

// check connection
if (mysqli_connect_errno()) exit('Connect failed: '. mysqli_connect_error());

// sql query for CREATE "userson" TABLE
$sql = "CREATE TABLE `userson` (
 `uvon` VARCHAR(32) PRIMARY KEY,
 `dt` INT(10) UNSIGNED NOT NULL
 ) CHARACTER SET utf8 COLLATE utf8_general_ci"; 

// Performs the $sql query on the server to create the table
if ($conn->query($sql) === TRUE) echo 'Table "userson" successfully created';
else echo 'Error: '. $conn->error;

$conn->close();
?>
  1. Now we create the script that Inserts, Deletes, and Selects data in the userson table (For explanations about the code, see the comments in script).
  • Add the code below in another php file (named usersmysql.php): In both file you must add your personal data for connecting to MySQL database, in the variables: $host, $user, $pass, and $dbname .

The code for usersmysql.php:

<?php
// Script Online Users and Visitors - coursesweb.net/php-mysql/
if(!isset($_SESSION)) session_start();         // start Session, if not already started

// HERE add your data for connecting to MySQ database
$host = 'localhost';           // MySQL server address
$user = 'root';                // User name
$pass = 'password';            // User`s password
$dbname = 'database';          // Database name

/*
 If you have an user registration script,
 replace $_SESSION['nume'] with the variable in which the user name is stored.
 You can get a free registration script from:  http://coursesweb.net/php-mysql/register-login-script-users-online_s2
*/

// get the user name if it is logged, or the visitors IP (and add the identifier)
$vst_id = '-vst-';         // an identifier to know that it is a visitor, not logged user
$uvon = isset($_SESSION['nume']) ? $_SESSION['nume'] : $_SERVER['SERVER_ADDR']. $vst_id;

$rgxvst = '/^([0-9\.]*)'. $vst_id. '/i';         // regexp to recognize the rows with visitors
$dt = time();                                    // current timestamp
$timeon = 120;             // number of secconds to keep a user online
$nrvst = 0;                                     // to store the number of visitors
$nrusr = 0;                                     // to store the number of usersrs
$usron = '';                                    // to store the name of logged users

// connect to the MySQL server
$conn = new mysqli($host, $user, $pass, $dbname);

// Define and execute the Delete, Insert/Update, and Select queries
$sqldel = "DELETE FROM `userson` WHERE `dt`<". ($dt - $timeon);
$sqliu = "INSERT INTO `userson` (`uvon`, `dt`) VALUES ('$uvon', $dt) ON DUPLICATE KEY UPDATE `dt`=$dt";
$sqlsel = "SELECT * FROM `userson`";

// Execute each query
if(!$conn->query($sqldel)) echo 'Error: '. $conn->error;
if(!$conn->query($sqliu)) echo 'Error: '. $conn->error;
$result = $conn->query($sqlsel);

// if the $result contains at least one row
if ($result->num_rows > 0) {
  // traverse the sets of results and set the number of online visitors and users ($nrvst, $nrusr)
  while($row = $result->fetch_assoc()) {
    if(preg_match($rgxvst, $row['uvon'])) $nrvst++;       // increment the visitors
    else {
      $nrusr++;                   // increment the users
      $usron .= '<br/> - <i>'.$row['uvon']. '</i>';          // stores the user's name
    }
  }
}

$conn->close();                  // close the MySQL connection

// the HTML code with data to be displayed
$reout = '<div id="uvon"><h4>Online: '. ($nrusr+$nrvst). '</h4>Visitors: '. $nrvst. '<br/>Users: '. $nrusr. $usron. '</div>';

// if access from <script>, with GET 'uvon=showon', adds the string to return into a JS statement
// in this way the script can also be included in .html files
if(isset($_GET['uvon']) && $_GET['uvon']=='showon') $reout = "document.write('$reout');";

echo $reout;             // output /display the result
?>
  1. After you have created these two php files on your server, run the "create_userson.php" on your browser to create the "userson" table.

  2. Include the usersmysql.php file in the php file in which you want to display the number of online users and visitors.

  3. Or, if you want to insert it in a ".html" file, add this code:

Examples using these scripts

• Including the "usersontxt.php` in a php file:

<!doctype html>

Counter Online Users and Visitors

• Including the "usersmysql.php" in a html file:

<!doctype html>
<html>
<head>
 <meta charset="utf-8" />
 <title>Counter Online Users and Visitors</title>
 <meta name="description" content="PHP script to count and show the number of online users and visitors" />
 <meta name="keywords" content="online users, online visitors" />
</head>
<body>

<!-- Includes the script ("usersontxt.php", or "usersmysql.php") -->
<script type="text/javascript" src="usersmysql.php?uvon=showon"></script>

</body>
</html>

Both scripts (with storing data in a text file on the server, or into a MySQL table) will display a result like this: Online: 5

Visitors: 3 Users: 2

  • MarPlo
  • Marius

CodeIgniter: How To Do a Select (Distinct Fieldname) MySQL Query

You can also run ->select('DISTINCT `field`', FALSE) and the second parameter tells CI not to escape the first argument.

With the second parameter as false, the output would be SELECT DISTINCT `field` instead of without the second parameter, SELECT `DISTINCT` `field`

Does a favicon have to be 32x32 or 16x16?

I don't see any up to date info listed here, so here goes:

To answer this question now, 2 favicons will not do it if you want your icon to look great everywhere. See the sizes below:

16 x 16 – Standard size for browsers
24 x 24 – IE9 pinned site size for user interface
32 x 32 – IE new page tab, Windows 7+ taskbar button, Safari Reading List sidebar
48 x 48 – Windows site
57 x 57 – iPod touch, iPhone up to 3G
60 x 60 – iPhone touch up to iOS7
64 x 64 – Windows site, Safari Reader List sidebar in HiDPI/Retina
70 x 70 – Win 8.1 Metro tile
72 x 72 – iPad touch up to iOS6
76 x 76 – iOS7
96 x 96 – GoogleTV
114 x 114 – iPhone retina touch up to iOS6
120 x 120 – iPhone retina touch iOS7
128 x 128 – Chrome Web Store app, Android
144 x 144 – IE10 Metro tile for pinned site, iPad retina up to iOS6
150 x 150 – Win 8.1 Metro tile
152 x 152 – iPad retina touch iOS7
196 x 196 – Android Chrome
310 x 150 – Win 8.1 wide Metro tile
310 x 310 – Win 8.1 Metro tile

How to add a custom button to the toolbar that calls a JavaScript function?

CKEditor 4

There are handy tutorials in the official CKEditor 4 documentation, that cover writing a plugin that inserts content into the editor, registers a button and shows a dialog window:

If you read these two, move on to Integrating Plugins with Advanced Content Filter.

CKEditor 5

So far there is one introduction article available:

CKEditor 5 Framework: Quick Start - Creating a simple plugin

I have never set any passwords to my keystore and alias, so how are they created?

Keystore name: "debug.keystore"

Keystore password: "android"

Key alias: "androiddebugkey"

Key password: "android"

I use this information and successfully generate Signed APK.

Assign value from successful promise resolve to external variable

This could be updated to ES6 with arrow functions and look like:

getFeed().then(data => vm.feed = data);

If you wish to use the async function, you could also do like that:

async function myFunction(){
    vm.feed = await getFeed();
    // do whatever you need with vm.feed below
 }

Disable/Enable button in Excel/VBA

I'm using excel 2010 and below VBA code worked fine for a Form Button. It removes the assigned macro from the button and assign in next command.

To disable:

ActiveSheet.Shapes("Button Name").OnAction = Empty
ActiveSheet.Shapes("Button Name").DrawingObject.Font.ColorIndex = 16

To enable:

ActiveSheet.Shapes("Button Name").OnAction = ActiveWorkbook.Name & "!Macro function Name with _Click"
ActiveSheet.Shapes("Button Name").DrawingObject.Font.ColorIndex = 1

Pls note "ActiveWorkbook.Name" stays as it is. Do not insert workbook name instead of "Name".

Executing a shell script from a PHP script

Without really knowing the complexity of the setup, I like the sudo route. First, you must configure sudo to permit your webserver to sudo run the given command as root. Then, you need to have the script that the webserver shell_exec's(testscript) run the command with sudo.

For A Debian box with Apache and sudo:

  1. Configure sudo:

    • As root, run the following to edit a new/dedicated configuration file for sudo:

      visudo -f /etc/sudoers.d/Webserver
      

      (or whatever you want to call your file in /etc/sudoers.d/)

    • Add the following to the file:

      www-data ALL = (root) NOPASSWD: <executable_file_path>
      

      where <executable_file_path> is the command that you need to be able to run as root with the full path in its name(say /bin/chown for the chown executable). If the executable will be run with the same arguments every time, you can add its arguments right after the executable file's name to further restrict its use.

      For example, say we always want to copy the same file in the /root/ directory, we would write the following:

      www-data ALL = (root) NOPASSWD: /bin/cp /root/test1 /root/test2
      
  2. Modify the script(testscript):

    Edit your script such that sudo appears before the command that requires root privileges(say sudo /bin/chown ... or sudo /bin/cp /root/test1 /root/test2). Make sure that the arguments specified in the sudo configuration file exactly match the arguments used with the executable in this file. So, for our example above, we would have the following in the script:

    sudo /bin/cp /root/test1 /root/test2
    

If you are still getting permission denied, the script file and it's parent directories' permissions may not allow the webserver to execute the script itself. Thus, you need to move the script to a more appropriate directory and/or change the script and parent directory's permissions to allow execution by www-data(user or group), which is beyond the scope of this tutorial.

Keep in mind:

When configuring sudo, the objective is to permit the command in it's most restricted form. For example, instead of permitting the general use of the cp command, you only allow the cp command if the arguments are, say, /root/test1 /root/test2. This means that cp's arguments(and cp's functionality cannot be altered).

CSS - Overflow: Scroll; - Always show vertical scroll bar?

Please note on iPad Safari, NoviceCoding's solution won't work if you have -webkit-overflow-scrolling: touch; somewhere in your CSS. The solution is either removing all the occurrences of -webkit-overflow-scrolling: touch; or putting -webkit-overflow-scrolling: auto; with NoviceCoding's solution.

Run-time error '3061'. Too few parameters. Expected 1. (Access 2007)

Thanks for John Doe's solution that helped a lot. Mine is very similar with some difference, using TempVars

Instead of :

      strSQL = "SELECT * FROM Table1 WHERE Name = Forms!Table!Control;"

I used:

      strSQL = "SELECT * FROM Query1"  , Query1 being common for other usage

Query1 as:

 "Select Field1, Field2 from Table1 where Id= [TempVars]![MyVar]

And similarly, removing [TempVars]![MyVar] from view solved the problem.

OR operator in switch-case?

Switch is not same as if-else-if.

Switch is used when there is one expression that gets evaluated to a value and that value can be one of predefined set of values. If you need to perform multiple boolean / comparions operations run-time then if-else-if needs to be used.

How to switch a user per task or set of tasks?

In Ansible 2.x, you can use the block for group of tasks:

- block:
    - name: checkout repo
      git:
        repo: https://github.com/some/repo.git
        version: master
        dest: "{{ dst }}"
    - name: change perms
      file:
      dest: "{{ dst }}"
      state: directory
      mode: 0755
      owner: some_user
  become: yes
  become_user: some user

How to use font-family lato?

Download it from here and extract LatoOFL.rar then go to TTF and open this font-face-generator click at Choose File choose font which you want to use and click at generate then download it and then go html file open it and you see the code like this

@font-face {
        font-family: "Lato Black";
        src: url('698242188-Lato-Bla.eot');
        src: url('698242188-Lato-Bla.eot?#iefix') format('embedded-opentype'),
        url('698242188-Lato-Bla.svg#Lato Black') format('svg'),
        url('698242188-Lato-Bla.woff') format('woff'),
        url('698242188-Lato-Bla.ttf') format('truetype');
        font-weight: normal;
        font-style: normal;
}
body{
    font-family: "Lato Black";
    direction: ltr;
}

change the src code and give the url where your this font directory placed, now you can use it at your website...

If you don't want to download it use this

<link type='text/css' href='http://fonts.googleapis.com/css?family=Lato:400,700' />

jQuery.animate() with css class only, without explicit styles

In many cases you're better off using CSS transitions for this, and in old browsers the easing will simply be instant. Most animations (like fade in/out) are very trivial to implement and the browser does all the legwork for you. https://developer.mozilla.org/en/docs/Web/CSS/transition

Enabling SSL with XAMPP

There is a better guide here for Windows:

https://shellcreeper.com/how-to-create-valid-ssl-in-localhost-for-xampp/

Basic steps:

  1. Create an SSL certificate for your local domain using this: See more details in the link above https://gist.github.com/turtlepod/3b8d8d0eef29de019951aa9d9dcba546 https://gist.github.com/turtlepod/e94928cddbfc46cfbaf8c3e5856577d0

  2. Install this cert in Windows (Trusted Root Certification Authorities) See more details in the link above

  3. Add the site in Windows hosts (C:\Windows\System32\drivers\etc\hosts) E.g.: 127.0.0.1 site.test

  4. Add the site in XAMPP conf (C:\xampp\apache\conf\extra\httpd-vhosts.conf) E.g.:

     <VirtualHost *:80>
        DocumentRoot "C:/xampp/htdocs"
        ServerName site.test
        ServerAlias *.site.test
     </VirtualHost>
     <VirtualHost *:443>
        DocumentRoot "C:/xampp/htdocs"
        ServerName site.test
        ServerAlias *.site.test
        SSLEngine on
        SSLCertificateFile "crt/site.test/server.crt"
        SSLCertificateKeyFile "crt/site.test/server.key"
     </VirtualHost>
    
  5. Restart Apache and your browser and it's done!

How to read an external local JSON file in JavaScript?

Just use $.getJSON and then $.each to iterate the pair Key /value. Content example for the JSON file and functional code:

    {
        {
            "key": "INFO",
            "value": "This is an example."
        }
    }

    var url = "file.json";         
    $.getJSON(url, function (data) {
        $.each(data, function (key, model) {
            if (model.key == "INFO") {
                console.log(model.value)
            }
        })
    });

Codeigniter's `where` and `or_where`

You can modify just the two lines:

->where('(library.available_until >=', date("Y-m-d H:i:s"), FALSE)
->or_where("library.available_until = '00-00-00 00:00:00')", NULL, FALSE)

EDIT:

Omitting the FALSE parameter would have placed the backticks before the brackets and make them a part of the table name/value, making the query unusable.

The NULL parameter is there just because the function requires the second parameter to be a value, and since we don't have one, we send NULL.

Html ordered list 1.1, 1.2 (Nested counters and scope) not working

Check this out :

http://jsfiddle.net/PTbGc/

Your issue seems to have been fixed.


What shows up for me (under Chrome and Mac OS X)

1. one
2. two
  2.1. two.one
  2.2. two.two
  2.3. two.three
3. three
  3.1 three.one
  3.2 three.two
    3.2.1 three.two.one
    3.2.2 three.two.two
4. four

How I did it


Instead of :

<li>Item 1</li>
<li>Item 2</li>
   <ol>
        <li>Subitem 1</li>
        <li>Subitem 2</li>
   </ol>

Do :

<li>Item 1</li>
<li>Item 2
   <ol>
        <li>Subitem 1</li>
        <li>Subitem 2</li>
   </ol>
</li>

How do I center an anchor element in CSS?

I think you can't do that with inline elements like anchor, span. But to make it work you have to set the display to block.

<a href="http://www.example.com" style="text-align:center;display:block;">example</a>

Android AudioRecord example

Here I am posting you the some code example which record good quality of sound using AudioRecord API.

Note: If you use in emulator the sound quality will not much good because we are using sample rate 8k which only supports in emulator. In device use sample rate to 44.1k for better quality.

public class Audio_Record extends Activity {
    private static final int RECORDER_SAMPLERATE = 8000;
    private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
    private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
    private AudioRecord recorder = null;
    private Thread recordingThread = null;
    private boolean isRecording = false;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        setButtonHandlers();
        enableButtons(false);

        int bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE,
                RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING); 
    }

    private void setButtonHandlers() {
        ((Button) findViewById(R.id.btnStart)).setOnClickListener(btnClick);
        ((Button) findViewById(R.id.btnStop)).setOnClickListener(btnClick);
    }

    private void enableButton(int id, boolean isEnable) {
        ((Button) findViewById(id)).setEnabled(isEnable);
    }

    private void enableButtons(boolean isRecording) {
        enableButton(R.id.btnStart, !isRecording);
        enableButton(R.id.btnStop, isRecording);
    }

    int BufferElements2Rec = 1024; // want to play 2048 (2K) since 2 bytes we use only 1024
    int BytesPerElement = 2; // 2 bytes in 16bit format

    private void startRecording() {

        recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
                RECORDER_SAMPLERATE, RECORDER_CHANNELS,
                RECORDER_AUDIO_ENCODING, BufferElements2Rec * BytesPerElement);

        recorder.startRecording();
        isRecording = true;
        recordingThread = new Thread(new Runnable() {
            public void run() {
                writeAudioDataToFile();
            }
        }, "AudioRecorder Thread");
        recordingThread.start();
    }

        //convert short to byte
    private byte[] short2byte(short[] sData) {
        int shortArrsize = sData.length;
        byte[] bytes = new byte[shortArrsize * 2];
        for (int i = 0; i < shortArrsize; i++) {
            bytes[i * 2] = (byte) (sData[i] & 0x00FF);
            bytes[(i * 2) + 1] = (byte) (sData[i] >> 8);
            sData[i] = 0;
        }
        return bytes;

    }

    private void writeAudioDataToFile() {
        // Write the output audio in byte

        String filePath = "/sdcard/voice8K16bitmono.pcm";
        short sData[] = new short[BufferElements2Rec];

        FileOutputStream os = null;
        try {
            os = new FileOutputStream(filePath);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        while (isRecording) {
            // gets the voice output from microphone to byte format

            recorder.read(sData, 0, BufferElements2Rec);
            System.out.println("Short writing to file" + sData.toString());
            try {
                // // writes the data to file from buffer
                // // stores the voice buffer
                byte bData[] = short2byte(sData);
                os.write(bData, 0, BufferElements2Rec * BytesPerElement);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        try {
            os.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void stopRecording() {
        // stops the recording activity
        if (null != recorder) {
            isRecording = false;
            recorder.stop();
            recorder.release();
            recorder = null;
            recordingThread = null;
        }
    }

    private View.OnClickListener btnClick = new View.OnClickListener() {
        public void onClick(View v) {
            switch (v.getId()) {
            case R.id.btnStart: {
                enableButtons(true);
                startRecording();
                break;
            }
            case R.id.btnStop: {
                enableButtons(false);
                stopRecording();
                break;
            }
            }
        }
    };

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            finish();
        }
        return super.onKeyDown(keyCode, event);
    }
}

For more detail try this AUDIORECORD BLOG.

Happy Coding !!

what is the multicast doing on 224.0.0.251?

I deactivated my "Arno's Iptables Firewall" for testing, and then the messages are gone

How do I pass JavaScript values to Scriptlet in JSP?

If you are saying you wanna pass javascript value from one jsp to another in javascript then use URLRewriting technique to pass javascript variable to next jsp file and access that in next jsp in request object.

Other wise you can't do it.

Question mark characters displaying within text, why is this?

This is going to be something to do with character encodings.

Are you sure the mirrored site has the same properties with regards to character encodings as your main server?

Depending on what sort of server you have, this may be a property of the server process itself, or it could be an environment variable.

For example, if this is a UNIX environment, perhaps try comparing LANG or LC_ALL?

See also here

Capture the screen shot using .NET

It's certainly possible to grab a screenshot using the .NET Framework. The simplest way is to create a new Bitmap object and draw into that using the Graphics.CopyFromScreen method.

Sample code:

using (Bitmap bmpScreenCapture = new Bitmap(Screen.PrimaryScreen.Bounds.Width, 
                                            Screen.PrimaryScreen.Bounds.Height))
using (Graphics g = Graphics.FromImage(bmpScreenCapture))
{
    g.CopyFromScreen(Screen.PrimaryScreen.Bounds.X,
                     Screen.PrimaryScreen.Bounds.Y,
                     0, 0,
                     bmpScreenCapture.Size,
                     CopyPixelOperation.SourceCopy);
}

Caveat: This method doesn't work properly for layered windows. Hans Passant's answer here explains the more complicated method required to get those in your screen shots.

How to resolve the error "Unable to access jarfile ApacheJMeter.jar errorlevel=1" while initiating Jmeter?

Try downloading apache-jmeter-2.6.zip from http://www.apache.org/dist/jmeter/binaries/

This contains the proper ApacheJMeter.jar that is needed to initiate.

Go to bin folder in the command prompt and try java -jar ApacheJMeter.jar if the download is correct this should open the GUI.

Edit on 23/08/2018:

How to add Headers on RESTful call using Jersey Client API

Try this!

Client client = ClientBuilder.newClient();

String jsonStr = client
            .target("http:....")
            .request(MediaType.APPLICATION_JSON)

            .header("WM_SVC.NAME", "RegistryService")
            .header("WM_QOS.CORRELATION_ID", "d1f0c0d2-2cf4-497b-b630-06d609d987b0")

            .get(String.class);

P.S You can add any number of headers like this!

How to upload and parse a CSV file in php

function doParseCSVFile($filesArray)
    {
        if ((file_exists($filesArray['frmUpload']['name'])) && (is_readable($filesArray['frmUpload']['name']))) { 

            $strFilePath = $filesArray['frmUpload']['tmp_name']; 

            $strFileHandle = fopen($strFilePath,"r");
            $line_of_text = fgetcsv($strFileHandle,1024,",","'"); 
            $line_of_text = fgetcsv($strFileHandle,1024,",","'"); 

            do { 
                if ($line_of_text[0]) { 
                    $strInsertSql = "INSERT INTO tbl_employee(employee_name, employee_code, employee_email, employee_designation, employee_number)VALUES('".addslashes($line_of_text[0])."', '".$line_of_text[1]."', '".addslashes($line_of_text[2])."', '".$line_of_text[3]."', '".$line_of_text[4]."')";
                    ExecuteQry($strInsertSql);
                }               
            } while (($line_of_text = fgetcsv($strFileHandle,1024,",","'"))!== FALSE);

        } else {
            return FALSE;
        }
    }

add created_at and updated_at fields to mongoose schemas

const mongoose = require('mongoose');
const config = require('config');
const util = require('util');

const Schema = mongoose.Schema;
const BaseSchema = function(obj, options) {
  if (typeof(options) == 'undefined') {
    options = {};
  }
  if (typeof(options['timestamps']) == 'undefined') {
    options['timestamps'] = true;
  }

  Schema.apply(this, [obj, options]);
};
util.inherits(BaseSchema, Schema);

var testSchema = new BaseSchema({
  jsonObject: { type: Object }
  , stringVar : { type: String }
});

Now you can use this, so that there is no need to include this option in every table

Rerender view on browser resize with React

For this reason better is if you use this data from CSS or JSON file data, and then with this data setting new state with this.state({width: "some value",height:"some value" }); or writing code who use data of width screen data in self work if you wish responsive show images

load scripts asynchronously

Here is my custom solution to eliminate render-blocking JavaScript:

// put all your JS files here, in correct order
const libs = {
  "jquery": "https://code.jquery.com/jquery-2.1.4.min.js",
  "bxSlider": "https://cdnjs.cloudflare.com/ajax/libs/bxslider/4.2.5/jquery.bxslider.min.js",
  "angular": "https://ajax.googleapis.com/ajax/libs/angularjs/1.5.0-beta.2/angular.min.js",
  "ngAnimate": "https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.5.0-beta.2/angular-animate.min.js"
}
const loadedLibs = {}
let counter = 0

const loadAsync = function(lib) {
  var http = new XMLHttpRequest()
  http.open("GET", libs[lib], true)
  http.onload = () => {
    loadedLibs[lib] = http.responseText
    if (++counter == Object.keys(libs).length) startScripts()
  }
  http.send()
}

const startScripts = function() {
  for (var lib in libs) eval(loadedLibs[lib])
  console.log("allLoaded")
}

for (var lib in libs) loadAsync(lib)

In short, it loads all your scripts asynchronously, and then executes them consequently.

Github repo: https://github.com/mudroljub/js-async-loader

What is the optimal algorithm for the game 2048?

I developed a 2048 AI using expectimax optimization, instead of the minimax search used by @ovolve's algorithm. The AI simply performs maximization over all possible moves, followed by expectation over all possible tile spawns (weighted by the probability of the tiles, i.e. 10% for a 4 and 90% for a 2). As far as I'm aware, it is not possible to prune expectimax optimization (except to remove branches that are exceedingly unlikely), and so the algorithm used is a carefully optimized brute force search.

Performance

The AI in its default configuration (max search depth of 8) takes anywhere from 10ms to 200ms to execute a move, depending on the complexity of the board position. In testing, the AI achieves an average move rate of 5-10 moves per second over the course of an entire game. If the search depth is limited to 6 moves, the AI can easily execute 20+ moves per second, which makes for some interesting watching.

To assess the score performance of the AI, I ran the AI 100 times (connected to the browser game via remote control). For each tile, here are the proportions of games in which that tile was achieved at least once:

2048: 100%
4096: 100%
8192: 100%
16384: 94%
32768: 36%

The minimum score over all runs was 124024; the maximum score achieved was 794076. The median score is 387222. The AI never failed to obtain the 2048 tile (so it never lost the game even once in 100 games); in fact, it achieved the 8192 tile at least once in every run!

Here's the screenshot of the best run:

32768 tile, score 794076

This game took 27830 moves over 96 minutes, or an average of 4.8 moves per second.

Implementation

My approach encodes the entire board (16 entries) as a single 64-bit integer (where tiles are the nybbles, i.e. 4-bit chunks). On a 64-bit machine, this enables the entire board to be passed around in a single machine register.

Bit shift operations are used to extract individual rows and columns. A single row or column is a 16-bit quantity, so a table of size 65536 can encode transformations which operate on a single row or column. For example, moves are implemented as 4 lookups into a precomputed "move effect table" which describes how each move affects a single row or column (for example, the "move right" table contains the entry "1122 -> 0023" describing how the row [2,2,4,4] becomes the row [0,0,4,8] when moved to the right).

Scoring is also done using table lookup. The tables contain heuristic scores computed on all possible rows/columns, and the resultant score for a board is simply the sum of the table values across each row and column.

This board representation, along with the table lookup approach for movement and scoring, allows the AI to search a huge number of game states in a short period of time (over 10,000,000 game states per second on one core of my mid-2011 laptop).

The expectimax search itself is coded as a recursive search which alternates between "expectation" steps (testing all possible tile spawn locations and values, and weighting their optimized scores by the probability of each possibility), and "maximization" steps (testing all possible moves and selecting the one with the best score). The tree search terminates when it sees a previously-seen position (using a transposition table), when it reaches a predefined depth limit, or when it reaches a board state that is highly unlikely (e.g. it was reached by getting 6 "4" tiles in a row from the starting position). The typical search depth is 4-8 moves.

Heuristics

Several heuristics are used to direct the optimization algorithm towards favorable positions. The precise choice of heuristic has a huge effect on the performance of the algorithm. The various heuristics are weighted and combined into a positional score, which determines how "good" a given board position is. The optimization search will then aim to maximize the average score of all possible board positions. The actual score, as shown by the game, is not used to calculate the board score, since it is too heavily weighted in favor of merging tiles (when delayed merging could produce a large benefit).

Initially, I used two very simple heuristics, granting "bonuses" for open squares and for having large values on the edge. These heuristics performed pretty well, frequently achieving 16384 but never getting to 32768.

Petr Morávek (@xificurk) took my AI and added two new heuristics. The first heuristic was a penalty for having non-monotonic rows and columns which increased as the ranks increased, ensuring that non-monotonic rows of small numbers would not strongly affect the score, but non-monotonic rows of large numbers hurt the score substantially. The second heuristic counted the number of potential merges (adjacent equal values) in addition to open spaces. These two heuristics served to push the algorithm towards monotonic boards (which are easier to merge), and towards board positions with lots of merges (encouraging it to align merges where possible for greater effect).

Furthermore, Petr also optimized the heuristic weights using a "meta-optimization" strategy (using an algorithm called CMA-ES), where the weights themselves were adjusted to obtain the highest possible average score.

The effect of these changes are extremely significant. The algorithm went from achieving the 16384 tile around 13% of the time to achieving it over 90% of the time, and the algorithm began to achieve 32768 over 1/3 of the time (whereas the old heuristics never once produced a 32768 tile).

I believe there's still room for improvement on the heuristics. This algorithm definitely isn't yet "optimal", but I feel like it's getting pretty close.


That the AI achieves the 32768 tile in over a third of its games is a huge milestone; I will be surprised to hear if any human players have achieved 32768 on the official game (i.e. without using tools like savestates or undo). I think the 65536 tile is within reach!

You can try the AI for yourself. The code is available at https://github.com/nneonneo/2048-ai.

DateTime "null" value

Although everyone has already given you the answer , I'll mention a way which makes it easy to pass a datetime into a function

[ERROR:cannot convert system.datetime? to system.datetime]

DateTime? dt = null;
DateTime dte = Convert.ToDateTime(dt);

Now you may pass dte inside the function without any issues.

Simplest way to detect a pinch

My answer is inspired by Jeffrey's answer. Where that answer gives a more abstract solution, I try to provide more concrete steps on how to potentially implement it. This is simply a guide, one that can be implemented more elegantly. For a more detailed example check out this tutorial by MDN web docs.

HTML:

<div id="zoom_here">....</div>

JS

<script>
var dist1=0;
function start(ev) {
           if (ev.targetTouches.length == 2) {//check if two fingers touched screen
               dist1 = Math.hypot( //get rough estimate of distance between two fingers
                ev.touches[0].pageX - ev.touches[1].pageX,
                ev.touches[0].pageY - ev.touches[1].pageY);                  
           }
    
    }
    function move(ev) {
           if (ev.targetTouches.length == 2 && ev.changedTouches.length == 2) {
                 // Check if the two target touches are the same ones that started
               var dist2 = Math.hypot(//get rough estimate of new distance between fingers
                ev.touches[0].pageX - ev.touches[1].pageX,
                ev.touches[0].pageY - ev.touches[1].pageY);
                //alert(dist);
                if(dist1>dist2) {//if fingers are closer now than when they first touched screen, they are pinching
                  alert('zoom out');
                }
                if(dist1<dist2) {//if fingers are further apart than when they first touched the screen, they are making the zoomin gesture
                   alert('zoom in');
                }
           }
           
    }
        document.getElementById ('zoom_here').addEventListener ('touchstart', start, false);
        document.getElementById('zoom_here').addEventListener('touchmove', move, false);
</script>

select into in mysql

In MySQL, It should be like this

INSERT INTO this_table_archive (col1, col2, ..., coln)
SELECT col1, col2, ..., coln
FROM this_table
WHERE entry_date < '2011-01-01 00:00:00';

MySQL Documentation

Cursor adapter and sqlite example

Really simple example.

Here is a really simple, but very effective, example. Once you have the basics down you can easily build off of it.

There are two main parts to using a Cursor Adapter with SQLite:

  1. Create a proper Cursor from the Database.

  2. Create a custom Cursor Adapter that takes the Cursor data from the database and pairs it with the View you intend to represent the data with.

1. Create a proper Cursor from the Database.

In your Activity:

SQLiteOpenHelper sqLiteOpenHelper = new SQLiteOpenHelper( 
        context, DATABASE_NAME, null, DATABASE_VERSION);

SQLiteDatabase sqLiteDatabase = sqLiteOpenHelper.getReadableDatabase();

String query = "SELECT * FROM clients ORDER BY company_name ASC"; // No trailing ';'

Cursor cursor = sqLiteDatabase.rawQuery(query, null); 

ClientCursorAdapter adapter = new ClientCursorAdapter(
        this, R.layout.clients_listview_row, cursor, 0 );

this.setListAdapter(adapter);

2. Create a Custom Cursor Adapter.

Note: Extending from ResourceCursorAdapter assumes you use XML to create your views.

public class ClientCursorAdapter extends ResourceCursorAdapter {

    public ClientCursorAdapter(Context context, int layout, Cursor cursor, int flags) {
        super(context, layout, cursor, flags);
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        TextView name = (TextView) view.findViewById(R.id.name);
        name.setText(cursor.getString(cursor.getColumnIndex("name")));

        TextView phone = (TextView) view.findViewById(R.id.phone);
        phone.setText(cursor.getString(cursor.getColumnIndex("phone")));
    }
}

Delegates in swift?

I got few corrections to post of @MakeAppPie

First at all when you are creating delegate protocol it should conform to Class protocol. Like in example below.

protocol ProtocolDelegate: class {
    func myMethod(controller:ViewController, text:String)
}

Second, your delegate should be weak to avoid retain cycle.

class ViewController: UIViewController {
    weak var delegate: ProtocolDelegate?
}

Last, you're safe because your protocol is an optional value. That means its "nil" message will be not send to this property. It's similar to conditional statement with respondToselector in objC but here you have everything in one line:

if ([self.delegate respondsToSelector:@selector(myMethod:text:)]) {
    [self.delegate myMethod:self text:@"you Text"];
}

Above you have an obj-C example and below you have Swift example of how it looks.

delegate?.myMethod(self, text:"your Text")

Can scripts be inserted with innerHTML?

You could do it like this:

var mydiv = document.getElementById("mydiv");
var content = "<script>alert(\"hi\");<\/script>";

mydiv.innerHTML = content;
var scripts = mydiv.getElementsByTagName("script");
for (var i = 0; i < scripts.length; i++) {
    eval(scripts[i].innerText);
}

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException Error

NullPointerExceptions are among the easier exceptions to diagnose, frequently. Whenever you get an exception in Java and you see the stack trace ( that's what your second quote-block is called, by the way ), you read from top to bottom. Often, you will see exceptions that start in Java library code or in native implementations methods, for diagnosis you can just skip past those until you see a code file that you wrote.

Then you like at the line indicated and look at each of the objects ( instantiated classes ) on that line -- one of them was not created and you tried to use it. You can start by looking up in your code to see if you called the constructor on that object. If you didn't, then that's your problem, you need to instantiate that object by calling new Classname( arguments ). Another frequent cause of NullPointerExceptions is accidentally declaring an object with local scope when there is an instance variable with the same name.

In your case, the exception occurred in your constructor for Workshop on line 75. <init> means the constructor for a class. If you look on that line in your code, you'll see the line

denimjeansButton.addItemListener(this);

There are fairly clearly two objects on this line: denimjeansButton and this. this is synonymous with the class instance you are currently in and you're in the constructor, so it can't be this. denimjeansButton is your culprit. You never instantiated that object. Either remove the reference to the instance variable denimjeansButton or instantiate it.

How to compile and run C files from within Notepad++ using NppExec plugin?

I recommend my solution. My situation: g++(cygwin) on win10

My solution: Write a .bat batch file and execute compiler in that batch. compileCpp.bat

@echo off  
set PATH=%PATH%;C:\cygwin64\bin\
rm %~n1.exe
c++.exe -g %~dpnx1 -o %~dpn1.exe
%~n1.exe  

Console:

NPP_EXEC: "runCpp"
NPP_SAVE: E:\hw.cpp
CD: E:\
Current directory: E:\
cmd /c C:\cygwin64\bin\compileCpp.bat "hw.cpp"
Process started >>>
Hello World<<< Process finished. (Exit code 0)
================ READY ================

How to listen state changes in react.js?

Using useState with useEffect as described above is absolutely correct way. But if getSearchResults function returns subscription then useEffect should return a function which will be responsible for unsubscribing the subscription . Returned function from useEffect will run before each change to dependency(name in above case) and on component destroy

Lua String replace

Try:

name = "^aH^ai"
name = name:gsub("%^a", "")

See also: http://lua-users.org/wiki/StringLibraryTutorial

How can I clear the content of a file?

The easiest way is:

File.WriteAllText(path, string.Empty)

However, I recommend you use FileStream because the first solution can throw UnauthorizedAccessException

using(FileStream fs = File.Open(path,FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
     lock(fs)
     {
          fs.SetLength(0);
     }
}

Getting the IP Address of a Remote Socket Endpoint

string ip = ((IPEndPoint)(testsocket.RemoteEndPoint)).Address.ToString();

NPM: npm-cli.js not found when running npm

You may also have this problem if in your path you have C:\Program Files\nodejs and C:\Program Files\nodejs\node_modules\npm\bin. Remove the latter from the path

How to declare an array inside MS SQL Server Stored Procedure?

You could declare a table variable (Declaring a variable of type table):

declare @MonthsSale table(monthnr int)
insert into @MonthsSale (monthnr) values (1)
insert into @MonthsSale (monthnr) values (2)
....

You can add extra columns as you like:

declare @MonthsSale table(monthnr int, totalsales tinyint)

You can update the table variable like any other table:

update m
set m.TotalSales = sum(s.SalesValue)
from @MonthsSale m
left join Sales s on month(s.SalesDt) = m.MonthNr

How do I set up NSZombieEnabled in Xcode 4?

I find this alternative more convenient:

  1. Click the "Run Button Dropdown"
  2. From the list choose Profile
  3. The program "Instruments" should open where you can also choose Zombies
  4. Now you can interact with your app and try to cause the error
  5. As soon as the error happens you should get a hint on when your object was released and therefore deallocated.

Zombies

As soon as a zombie is detected you then get a neat "Zombie Stack" that shows you when the object in question was allocated and where it was retained or released:

Event Type    RefCt     Responsible Caller
Malloc            1     -[MyViewController loadData:]
Retain            2     -[MyDataManager initWithBaseURL:]
Release           1     -[MyDataManager initWithBaseURL:]
Release           0     -[MyViewController loadData:]
Zombie           -1     -[MyService prepareURLReuqest]

Advantages compared to using the diagnostic tab of the Xcode Schemes:

  1. If you forget to uncheck the option in the diagnostic tab there no objects will be released from memory.

  2. You get a more detailed stack that shows you in what methods your corrupt object was allocated / released or retained.

MVC Razor Radio Button

I done this in a way like:

  @Html.RadioButtonFor(model => model.Gender, "M", false)@Html.Label("Male")
  @Html.RadioButtonFor(model => model.Gender, "F", false)@Html.Label("Female")

Convert integer to class Date

Another way to get the same result:

date <- strptime(v,format="%Y%m%d")

Code for a simple JavaScript countdown timer?

_x000D_
_x000D_
// Javascript Countdown_x000D_
// Version 1.01 6/7/07 (1/20/2000)_x000D_
// by TDavid at http://www.tdscripts.com/_x000D_
var now = new Date();_x000D_
var theevent = new Date("Nov 13 2017 22:05:01");_x000D_
var seconds = (theevent - now) / 1000;_x000D_
var minutes = seconds / 60;_x000D_
var hours = minutes / 60;_x000D_
var days = hours / 24;_x000D_
ID = window.setTimeout("update();", 1000);_x000D_
_x000D_
function update() {_x000D_
  now = new Date();_x000D_
  seconds = (theevent - now) / 1000;_x000D_
  seconds = Math.round(seconds);_x000D_
  minutes = seconds / 60;_x000D_
  minutes = Math.round(minutes);_x000D_
  hours = minutes / 60;_x000D_
  hours = Math.round(hours);_x000D_
  days = hours / 24;_x000D_
  days = Math.round(days);_x000D_
  document.form1.days.value = days;_x000D_
  document.form1.hours.value = hours;_x000D_
  document.form1.minutes.value = minutes;_x000D_
  document.form1.seconds.value = seconds;_x000D_
  ID = window.setTimeout("update();", 1000);_x000D_
}
_x000D_
<p><font face="Arial" size="3">Countdown To January 31, 2000, at 12:00: </font>_x000D_
</p>_x000D_
<form name="form1">_x000D_
  <p>Days_x000D_
    <input type="text" name="days" value="0" size="3">Hours_x000D_
    <input type="text" name="hours" value="0" size="4">Minutes_x000D_
    <input type="text" name="minutes" value="0" size="7">Seconds_x000D_
    <input type="text" name="seconds" value="0" size="7">_x000D_
  </p>_x000D_
</form>
_x000D_
_x000D_
_x000D_

Java: how to convert HashMap<String, Object> to array

You may try this too.

public static String[][] getArrayFromHash(Hashtable<String,String> data){
        String[][] str = null;
        {
            Object[] keys = data.keySet().toArray();
            Object[] values = data.values().toArray();
            str = new String[keys.length][values.length];
            for(int i=0;i<keys.length;i++) {
                str[0][i] = (String)keys[i];
                str[1][i] = (String)values[i];
            }
        }
        return str;
    }

Here I am using String as return type. You may change it to required return type by you.

javascript filter array of objects

You could utilize jQuery.filter() function to return elements from a subset of the matching elements.

_x000D_
_x000D_
var names = [_x000D_
    { name : "Joe", age:20, email: "[email protected]"},_x000D_
    { name : "Mike", age:50, email: "[email protected]"},_x000D_
    { name : "Joe", age:45, email: "[email protected]"}_x000D_
   ];_x000D_
   _x000D_
   _x000D_
var filteredNames = $(names).filter(function( idx ) {_x000D_
    return names[idx].name === "Joe" && names[idx].age < 30;_x000D_
}); _x000D_
_x000D_
$(filteredNames).each(function(){_x000D_
     $('#output').append(this.name);_x000D_
});
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
_x000D_
<div id="output"/>
_x000D_
_x000D_
_x000D_

Convert Unicode to ASCII without errors in Python

For broken consoles like cmd.exe and HTML output you can always use:

my_unicode_string.encode('ascii','xmlcharrefreplace')

This will preserve all the non-ascii chars while making them printable in pure ASCII and in HTML.

WARNING: If you use this in production code to avoid errors then most likely there is something wrong in your code. The only valid use case for this is printing to a non-unicode console or easy conversion to HTML entities in an HTML context.

And finally, if you are on windows and use cmd.exe then you can type chcp 65001 to enable utf-8 output (works with Lucida Console font). You might need to add myUnicodeString.encode('utf8').

What are the differences among grep, awk & sed?

Short definition:

grep: search for specific terms in a file

#usage
$ grep This file.txt
Every line containing "This"
Every line containing "This"
Every line containing "This"
Every line containing "This"

$ cat file.txt
Every line containing "This"
Every line containing "This"
Every line containing "That"
Every line containing "This"
Every line containing "This"

Now awk and sed are completly different than grep. awk and sed are text processors. Not only do they have the ability to find what you are looking for in text, they have the ability to remove, add and modify the text as well (and much more).

awk is mostly used for data extraction and reporting. sed is a stream editor
Each one of them has its own functionality and specialties.

Example
Sed

$ sed -i 's/cat/dog/' file.txt
# this will replace any occurrence of the characters 'cat' by 'dog'

Awk

$ awk '{print $2}' file.txt
# this will print the second column of file.txt

Basic awk usage:
Compute sum/average/max/min/etc. what ever you may need.

$ cat file.txt
A 10
B 20
C 60
$ awk 'BEGIN {sum=0; count=0; OFS="\t"} {sum+=$2; count++} END {print "Average:", sum/count}' file.txt
Average:    30

I recommend that you read this book: Sed & Awk: 2nd Ed.

It will help you become a proficient sed/awk user on any unix-like environment.

Get yesterday's date in bash on Linux, DST-safe

date under Mac OSX is slightly different.

For yesterday

date -v-1d +%F

For Last week

date -v-1w +%F

Does VBScript have a substring() function?

Yes, Mid.

Dim sub_str
sub_str = Mid(source_str, 10, 5)

The first parameter is the source string, the second is the start index, and the third is the length.

@bobobobo: Note that VBScript strings are 1-based, not 0-based. Passing 0 as an argument to Mid results in "invalid procedure call or argument Mid".

How to replace four spaces with a tab in Sublime Text 2?

You could add easy key binding:

Preference > Key binding - user :

[
    { "keys": ["super+l"], "command": "reindent"},
]

Now select the line or file and hit: command + l

Find and Replace Inside a Text File from a Bash Command

I found this thread among others and I agree it contains the most complete answers so I'm adding mine too:

  1. sed and ed are so useful...by hand. Look at this code from @Johnny:

    sed -i -e 's/abc/XYZ/g' /tmp/file.txt
    
  2. When my restriction is to use it in a shell script, no variable can be used inside in place of "abc" or "XYZ". The BashFAQ seems to agree with what I understand at least. So, I can't use:

    x='abc'
    y='XYZ'
    sed -i -e 's/$x/$y/g' /tmp/file.txt
    #or,
    sed -i -e "s/$x/$y/g" /tmp/file.txt
    

    but, what can we do? As, @Johnny said use a while read... but, unfortunately that's not the end of the story. The following worked well with me:

    #edit user's virtual domain
    result=
    #if nullglob is set then, unset it temporarily
    is_nullglob=$( shopt -s | egrep -i '*nullglob' )
    if [[ is_nullglob ]]; then
       shopt -u nullglob
    fi
    while IFS= read -r line; do
       line="${line//'<servername>'/$server}"
       line="${line//'<serveralias>'/$alias}"
       line="${line//'<user>'/$user}"
       line="${line//'<group>'/$group}"
       result="$result""$line"'\n'
    done < $tmp
    echo -e $result > $tmp
    #if nullglob was set then, re-enable it
    if [[ is_nullglob ]]; then
       shopt -s nullglob
    fi
    #move user's virtual domain to Apache 2 domain directory
    ......
    
  3. As one can see if nullglob is set then, it behaves strangely when there is a string containing a * as in:

    <VirtualHost *:80>
     ServerName www.example.com
    

    which becomes

    <VirtualHost ServerName www.example.com
    

    there is no ending angle bracket and Apache2 can't even load.

  4. This kind of parsing should be slower than one-hit search and replace but, as you already saw, there are four variables for four different search patterns working out of one parse cycle.

The most suitable solution I can think of with the given assumptions of the problem.

Unable to verify leaf signature

I had an issue with my Apache configuration after installing a GoDaddy certificate on a subdomain. I originally thought it might be an issue with Node not sending a Server Name Indicator (SNI), but that wasn't the case. Analyzing the subdomain's SSL certificate with https://www.ssllabs.com/ssltest/ returned the error Chain issues: Incomplete.

After adding the GoDaddy provided gd_bundle-g2-g1.crt file via the SSLCertificateChainFile Apache directive, Node was able to connect over HTTPS and the error went away.

JavaScript naming conventions

That's an individual question that could depend on how you're working. Some people like to put the variable type at the begining of the variable, like "str_message". And some people like to use underscore between their words ("my_message") while others like to separate them with upper-case letters ("myMessage").

I'm often working with huge JavaScript libraries with other people, so functions and variables (except the private variables inside functions) got to start with the service's name to avoid conflicts, as "guestbook_message".

In short: english, lower-cased, well-organized variable and function names is preferable according to me. The names should describe their existence rather than being short.

php multidimensional array get values

This is the way to iterate on this array:

foreach($hotels as $row) {
       foreach($row['rooms'] as $k) {
             echo $k['boards']['board_id'];
             echo $k['boards']['price'];
       }
}

You want to iterate on the hotels and the rooms (the ones with numeric indexes), because those seem to be the "collections" in this case. The other arrays only hold and group properties.

How add spaces between Slick carousel item

simply add padding on to the slick-side class will do

.slick-slider .slick-slide {
  padding: 0 15px;
}

TypeScript: correct way to do string equality?

If you know x and y are both strings, using === is not strictly necessary, but is still good practice.

Assuming both variables actually are strings, both operators will function identically. However, TS often allows you to pass an object that meets all the requirements of string rather than an actual string, which may complicate things.

Given the possibility of confusion or changes in the future, your linter is probably correct in demanding ===. Just go with that.

Selecting with complex criteria from pandas.DataFrame

Sure! Setup:

>>> import pandas as pd
>>> from random import randint
>>> df = pd.DataFrame({'A': [randint(1, 9) for x in range(10)],
                   'B': [randint(1, 9)*10 for x in range(10)],
                   'C': [randint(1, 9)*100 for x in range(10)]})
>>> df
   A   B    C
0  9  40  300
1  9  70  700
2  5  70  900
3  8  80  900
4  7  50  200
5  9  30  900
6  2  80  700
7  2  80  400
8  5  80  300
9  7  70  800

We can apply column operations and get boolean Series objects:

>>> df["B"] > 50
0    False
1     True
2     True
3     True
4    False
5    False
6     True
7     True
8     True
9     True
Name: B
>>> (df["B"] > 50) & (df["C"] == 900)
0    False
1    False
2     True
3     True
4    False
5    False
6    False
7    False
8    False
9    False

[Update, to switch to new-style .loc]:

And then we can use these to index into the object. For read access, you can chain indices:

>>> df["A"][(df["B"] > 50) & (df["C"] == 900)]
2    5
3    8
Name: A, dtype: int64

but you can get yourself into trouble because of the difference between a view and a copy doing this for write access. You can use .loc instead:

>>> df.loc[(df["B"] > 50) & (df["C"] == 900), "A"]
2    5
3    8
Name: A, dtype: int64
>>> df.loc[(df["B"] > 50) & (df["C"] == 900), "A"].values
array([5, 8], dtype=int64)
>>> df.loc[(df["B"] > 50) & (df["C"] == 900), "A"] *= 1000
>>> df
      A   B    C
0     9  40  300
1     9  70  700
2  5000  70  900
3  8000  80  900
4     7  50  200
5     9  30  900
6     2  80  700
7     2  80  400
8     5  80  300
9     7  70  800

Note that I accidentally typed == 900 and not != 900, or ~(df["C"] == 900), but I'm too lazy to fix it. Exercise for the reader. :^)

What is an ORM, how does it work, and how should I use one?

Can anyone give me a brief explanation...

Sure.

ORM stands for "Object to Relational Mapping" where

  • The Object part is the one you use with your programming language ( python in this case )

  • The Relational part is a Relational Database Manager System ( A database that is ) there are other types of databases but the most popular is relational ( you know tables, columns, pk fk etc eg Oracle MySQL, MS-SQL )

  • And finally the Mapping part is where you do a bridge between your objects and your tables.

In applications where you don't use a ORM framework you do this by hand. Using an ORM framework would allow you do reduce the boilerplate needed to create the solution.

So let's say you have this object.

 class Employee:
      def __init__( self, name ): 
          self.__name = name

       def getName( self ):
           return self.__name

       #etc.

and the table

   create table employee(
          name varcar(10),
          -- etc  
    )

Using an ORM framework would allow you to map that object with a db record automagically and write something like:

   emp = Employee("Ryan")

   orm.save( emp )

And have the employee inserted into the DB.

Oops it was not that brief but I hope it is simple enough to catch other articles you read.

Removing elements from array Ruby

[1,3].inject([1,1,1,2,2,3]) do |memo,element|
  memo.tap do |memo|
    i = memo.find_index(e)
    memo.delete_at(i) if i
  end
end

How to move div vertically down using CSS

if div.title is a div then put this:

left: 0;
bottom: 0;

How to detect installed version of MS-Office?

        public string WinWordVersion
        {
            get
            {
                string _version = string.Empty;
                Word.Application WinWord = new Word.Application();   

                switch (WinWord.Version.ToString())
                {
                    case "7.0":  _version = "95";
                        break;
                    case "8.0": _version = "97";
                        break;
                    case "9.0": _version = "2000";
                        break;
                    case "10.0": _version = "2002";
                        break;
                    case "11.0":  _version = "2003";
                        break;
                    case "12.0": _version = "2007";
                        break;
                    case "14.0": _version = "2010";
                        break;
                    case "15.0":  _version = "2013";
                        break;
                    case "16.0": _version = "2016";
                        break;
                    default:                            
                        break;
                }

                return WinWord.Caption + " " + _version;
            }
        }

Invoke JSF managed bean action on page load

@PostConstruct is run ONCE in first when Bean Created. the solution is create a Unused property and Do your Action in Getter method of this property and add this property to your .xhtml file like this :

<h:inputHidden  value="#{loginBean.loginStatus}"/>

and in your bean code:

public void setLoginStatus(String loginStatus) {
    this.loginStatus = loginStatus;
}

public String getLoginStatus()  {
    // Do your stuff here.
    return loginStatus;
}

Picking a random element from a set

PHP, using MT:

$items_array = array("alpha", "bravo", "charlie");
$last_pos = count($items_array) - 1;
$random_pos = mt_rand(0, $last_pos);
$random_item = $items_array[$random_pos];

Reading from a text file and storing in a String

These are the necersary imports:

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

And this is a method that will allow you to read from a File by passing it the filename as a parameter like this: readFile("yourFile.txt");

String readFile(String fileName) throws IOException {
    BufferedReader br = new BufferedReader(new FileReader(fileName));
    try {
        StringBuilder sb = new StringBuilder();
        String line = br.readLine();

        while (line != null) {
            sb.append(line);
            sb.append("\n");
            line = br.readLine();
        }
        return sb.toString();
    } finally {
        br.close();
    }
}

How do I sort arrays using vbscript?

Disconnected recordsets can be useful.

Const adVarChar = 200  'the SQL datatype is varchar

'Create a disconnected recordset
Set rs = CreateObject("ADODB.RECORDSET")
rs.Fields.append "SortField", adVarChar, 25

rs.CursorType = adOpenStatic
rs.Open
rs.AddNew "SortField", "Some data"
rs.Update
rs.AddNew "SortField", "All data"
rs.Update

rs.Sort = "SortField"

rs.MoveFirst

Do Until rs.EOF
    strList=strList & vbCrLf & rs.Fields("SortField")        
    rs.MoveNext
Loop 

MsgBox strList

PHP: How to send HTTP response code?

I just found this question and thought it needs a more comprehensive answer:

As of PHP 5.4 there are three methods to accomplish this:

Assembling the response code on your own (PHP >= 4.0)

The header() function has a special use-case that detects a HTTP response line and lets you replace that with a custom one

header("HTTP/1.1 200 OK");

However, this requires special treatment for (Fast)CGI PHP:

$sapi_type = php_sapi_name();
if (substr($sapi_type, 0, 3) == 'cgi')
    header("Status: 404 Not Found");
else
    header("HTTP/1.1 404 Not Found");

Note: According to the HTTP RFC, the reason phrase can be any custom string (that conforms to the standard), but for the sake of client compatibility I do not recommend putting a random string there.

Note: php_sapi_name() requires PHP 4.0.1

3rd argument to header function (PHP >= 4.3)

There are obviously a few problems when using that first variant. The biggest of which I think is that it is partly parsed by PHP or the web server and poorly documented.

Since 4.3, the header function has a 3rd argument that lets you set the response code somewhat comfortably, but using it requires the first argument to be a non-empty string. Here are two options:

header(':', true, 404);
header('X-PHP-Response-Code: 404', true, 404);

I recommend the 2nd one. The first does work on all browsers I have tested, but some minor browsers or web crawlers may have a problem with a header line that only contains a colon. The header field name in the 2nd. variant is of course not standardized in any way and could be modified, I just chose a hopefully descriptive name.

http_response_code function (PHP >= 5.4)

The http_response_code() function was introduced in PHP 5.4, and it made things a lot easier.

http_response_code(404);

That's all.

Compatibility

Here is a function that I have cooked up when I needed compatibility below 5.4 but wanted the functionality of the "new" http_response_code function. I believe PHP 4.3 is more than enough backwards compatibility, but you never know...

// For 4.3.0 <= PHP <= 5.4.0
if (!function_exists('http_response_code'))
{
    function http_response_code($newcode = NULL)
    {
        static $code = 200;
        if($newcode !== NULL)
        {
            header('X-PHP-Response-Code: '.$newcode, true, $newcode);
            if(!headers_sent())
                $code = $newcode;
        }       
        return $code;
    }
}

CodeIgniter - how to catch DB errors?

In sybase_driver.php

/**
* Manejador de Mensajes de Error Sybase
* Autor: Isaí Moreno
* Fecha: 06/Nov/2019
*/

static  $CODE_ERROR_SYBASE;

public static function SetCodeErrorSybase($Code) {
    if ($Code != 3621) {  /*No se toma en cuenta el código de command aborted*/
        CI_DB_sybase_driver::$CODE_ERROR_SYBASE = trim(CI_DB_sybase_driver::$CODE_ERROR_SYBASE.' '.$Code);       
    }
}

public static function GetCodeErrorSybase() {               
    return CI_DB_sybase_driver::$CODE_ERROR_SYBASE;
}

public static function msg_handler($msgnumber, $severity, $state, $line, $text)
{       
    log_message('info', 'CI_DB_sybase_driver - CODE ERROR ['.$msgnumber.'] Mensaje - '.$text);
    CI_DB_sybase_driver::SetCodeErrorSybase($msgnumber);   
}

// ------------------------------------------------------------------------

Add and modify the following methods in the same sybase_driver.php file

/**
 * The error message number
 *
 * @access  private
 * @return  integer
 */
function _error_number()
{
    // Are error numbers supported?
    return CI_DB_sybase_driver::GetCodeErrorSybase();
}

function _sybase_set_message_handler()
{
    // Are error numbers supported?     
    return sybase_set_message_handler('CI_DB_sybase_driver::msg_handler');
}

Implement in the function of a controller.

public function Eliminar_DUPLA(){       
    if($this->session->userdata($this->config->item('mycfg_session_object_name'))){     
        //***/
        $Operacion_Borrado_Exitosa=false;
        $this->db->trans_begin();

        $this->db->_sybase_set_message_handler();  <<<<<------- Activar Manejador de errores de sybase
        $Dupla_Eliminada=$this->Mi_Modelo->QUERY_Eliminar_Dupla($PARAMETROS);                   

        if ($Dupla_Eliminada){
            $this->db->trans_commit();
            MostrarNotificacion("Se eliminó DUPLA exitosamente","OK",true);
            $Operacion_Borrado_Exitosa=true;
        }else{
            $Error = $this->db->_error_number();  <<<<----- Obtengo el código de error de sybase para personilzar mensaje al usuario    
            $this->db->trans_rollback();                
            MostrarNotificacion("Ocurrio un error al intentar eliminar Dupla","Error",true);
            if ($Error == 547) {
                MostrarNotificacion("<strong>Código de error :[".$Error.']. No se puede eliminar documento Padre.</strong>',"Error",true);
            }  else {                   
                MostrarNotificacion("<strong>Código de Error :[".$Error.']</strong><br>',"Error",true);                 
            }
        }

        echo "@".Obtener_Contador_Notificaciones();
        if ($Operacion_Borrado_Exitosa){
            echo "@T";
        }else{
            echo "@F";
        }
    }else{
        redirect($this->router->default_controller);
    }

}

In the log you can check the codes and messages sent by the database server.

INFO - 2019-11-06 19:26:33 -> CI_DB_sybase_driver - CODE ERROR [547] Message - Dependent foreign key constraint violation in a referential integrity constraint. dbname = 'database', table name = 'mitabla', constraint name = 'FK_SR_RELAC_REFERENCE_SR_mitabla'. INFO - 2019-11-06 19:26:33 -> CI_DB_sybase_driver - CODE ERROR [3621] Message - Command has been aborted. ERROR - 2019-11-06 19:26:33 -> Query error: - Invalid query: delete from mitabla where ID = 1019.

The following untracked working tree files would be overwritten by merge, but I don't care

In my case when I had this problem. I had a local file that I had renamed on the remote.

When trying to git pull Git told me the new filename was not tracked -- which it was on the remote although it didn't yet exist on local.

Because there was no instance of it locally I couldn't do git pull until I did git rm on the old filename (which wasn't obvious at first because of my stupid idea of renaming it).

Can't get ScriptManager.RegisterStartupScript in WebControl nested in UpdatePanel to work

I had an issue using this in a user control (in a page this worked fine); the Button1 is inside an updatepanel, and the scriptmanager is on the usercontrol.

protected void Button1_Click(object sender, EventArgs e)  
{  
    string scriptstring = "alert('Welcome');";  
    ScriptManager.RegisterStartupScript(this, this.GetType(), "alertscript", scriptstring, true);  
}

Now it seems you have to be careful with the first two arguments, they need to reference your page, not your control

ScriptManager.RegisterStartupScript(this.Page, this.Page.GetType(), "alertscript", scriptstring, true);

How to change font-color for disabled input?

It seems nobody found a solution for this. I don't have one based on only css neither but by using this JavaScript trick I usually can handle disabled input fields.

Remember that disabled fields always follow the style that they got before becoming disabled. So the trick would be 1- Enabling them 2-Change the class 3- Disable them again. Since this happens very fast user cannot understand what happened.

A simple JavaScript code would be something like:

function changeDisabledClass (id, disabledClass){
var myInput=document.getElementById(id);
myInput.disabled=false;             //First make sure it is not disabled
myInput.className=disabledClass;    //change the class
myInput.disabled=true;             //Re-disable it
}

Difference between natural join and inner join

SQL is not faithful to the relational model in many ways. The result of a SQL query is not a relation because it may have columns with duplicate names, 'anonymous' (unnamed) columns, duplicate rows, nulls, etc. SQL doesn't treat tables as relations because it relies on column ordering etc.

The idea behind NATURAL JOIN in SQL is to make it easier to be more faithful to the relational model. The result of the NATURAL JOIN of two tables will have columns de-duplicated by name, hence no anonymous columns. Similarly, UNION CORRESPONDING and EXCEPT CORRESPONDING are provided to address SQL's dependence on column ordering in the legacy UNION syntax.

However, as with all programming techniques it requires discipline to be useful. One requirement for a successful NATURAL JOIN is consistently named columns, because joins are implied on columns with the same names (it is a shame that the syntax for renaming columns in SQL is verbose but the side effect is to encourage discipline when naming columns in base tables and VIEWs :)

Note a SQL NATURAL JOIN is an equi-join**, however this is no bar to usefulness. Consider that if NATURAL JOIN was the only join type supported in SQL it would still be relationally complete.

While it is indeed true that any NATURAL JOIN may be written using INNER JOIN and projection (SELECT), it is also true that any INNER JOIN may be written using product (CROSS JOIN) and restriction (WHERE); further note that a NATURAL JOIN between tables with no column names in common will give the same result as CROSS JOIN. So if you are only interested in results that are relations (and why ever not?!) then NATURAL JOIN is the only join type you need. Sure, it is true that from a language design perspective shorthands such as INNER JOIN and CROSS JOIN have their value, but also consider that almost any SQL query can be written in 10 syntactically different, but semantically equivalent, ways and this is what makes SQL optimizers so very hard to develop.

Here are some example queries (using the usual parts and suppliers database) that are semantically equivalent:

SELECT *
  FROM S NATURAL JOIN SP;

-- Must disambiguate and 'project away' duplicate SNO attribute
SELECT S.SNO, SNAME, STATUS, CITY, PNO, QTY
  FROM S INNER JOIN SP 
          USING (SNO);                        

-- Alternative projection
SELECT S.*, PNO, QTY
  FROM S INNER JOIN SP 
          ON S.SNO = SP.SNO;

-- Same columns, different order == equivalent?!
SELECT SP.*, S.SNAME, S.STATUS, S.CITY
  FROM S INNER JOIN SP 
      ON S.SNO = SP.SNO;

-- 'Old school'
SELECT S.*, PNO, QTY
  FROM S, SP 
 WHERE S.SNO = SP.SNO;

** Relational natural join is not an equijoin, it is a projection of one. – philipxy

React-Redux: Actions must be plain objects. Use custom middleware for async actions

Make use of Arrow functions it improves the readability of code. No need to return anything in API.fetchComments, Api call is asynchronous when the request is completed then will get the response, there you have to just dispatch type and data.

Below code does the same job by making use of Arrow functions.

export const bindComments = postId => {
  return dispatch => {
    API.fetchComments(postId).then(comments => {
      dispatch({
        type: BIND_COMMENTS,
        comments,
        postId
      });
    });
  };
};

How can I tell which button was clicked in a PHP form submit?

In HTML:

<input type="submit" id="btnSubmit" name="btnSubmit" value="Save Changes" />
<input type="submit" id="btnDelete" name="btnDelete" value="Delete" />

In PHP:

if (isset($_POST["btnSubmit"])){
  // "Save Changes" clicked
} else if (isset($_POST["btnDelete"])){
  // "Delete" clicked
}

BeautifulSoup: extract text from anchor tag

All the above answers really help me to construct my answer, because of this I voted for all the answers that other users put it out: But I finally put together my own answer to exact problem I was dealing with:

As question clearly defined I had to access some of the siblings and its children in a dom structure: This solution will iterate over the images in the dom structure and construct image name using product title and save the image to the local directory.

import urlparse
from urllib2 import urlopen
from urllib import urlretrieve
from BeautifulSoup import BeautifulSoup as bs
import requests

def getImages(url):
    #Download the images
    r = requests.get(url)
    html = r.text
    soup = bs(html)
    output_folder = '~/amazon'
    #extracting the images that in div(s)
    for div in soup.findAll('div', attrs={'class':'image'}):
        modified_file_name = None
        try:
            #getting the data div using findNext
            nextDiv =  div.findNext('div', attrs={'class':'data'})
            #use findNext again on previous object to get to the anchor tag
            fileName = nextDiv.findNext('a').text
            modified_file_name = fileName.replace(' ','-') + '.jpg'
        except TypeError:
            print 'skip'
        imageUrl = div.find('img')['src']
        outputPath = os.path.join(output_folder, modified_file_name)
        urlretrieve(imageUrl, outputPath)

if __name__=='__main__':
    url = r'http://www.amazon.com/s/ref=sr_pg_1?rh=n%3A172282%2Ck%3Adigital+camera&keywords=digital+camera&ie=UTF8&qid=1343600585'
    getImages(url)

Access Controller method from another controller in Laravel 5

namespace App\Http\Controllers;

//call the controller you want to use its methods
use App\Http\Controllers\AdminController;

use Illuminate\Http\Request;

use App\Http\Requests;

class MealController extends Controller
   {
      public function try_call( AdminController $admin){
         return $admin->index();   
    }
   }

JPA CriteriaBuilder - How to use "IN" comparison operator

If I understand well, you want to Join ScheduleRequest with User and apply the in clause to the userName property of the entity User.

I'd need to work a bit on this schema. But you can try with this trick, that is much more readable than the code you posted, and avoids the Join part (because it handles the Join logic outside the Criteria Query).

List<String> myList = new ArrayList<String> ();
for (User u : usersList) {
    myList.add(u.getUsername());
}
Expression<String> exp = scheduleRequest.get("createdBy");
Predicate predicate = exp.in(myList);
criteria.where(predicate);

In order to write more type-safe code you could also use Metamodel by replacing this line:

Expression<String> exp = scheduleRequest.get("createdBy");

with this:

Expression<String> exp = scheduleRequest.get(ScheduleRequest_.createdBy);

If it works, then you may try to add the Join logic into the Criteria Query. But right now I can't test it, so I prefer to see if somebody else wants to try.


Not a perfect answer though may be code snippets might help.

public <T> List<T> findListWhereInCondition(Class<T> clazz,
            String conditionColumnName, Serializable... conditionColumnValues) {
        QueryBuilder<T> queryBuilder = new QueryBuilder<T>(clazz);
        addWhereInClause(queryBuilder, conditionColumnName,
                conditionColumnValues);
        queryBuilder.select();
        return queryBuilder.getResultList();

    }


private <T> void addWhereInClause(QueryBuilder<T> queryBuilder,
            String conditionColumnName, Serializable... conditionColumnValues) {

        Path<Object> path = queryBuilder.root.get(conditionColumnName);
        In<Object> in = queryBuilder.criteriaBuilder.in(path);
        for (Serializable conditionColumnValue : conditionColumnValues) {
            in.value(conditionColumnValue);
        }
        queryBuilder.criteriaQuery.where(in);

    }

Scale image to fit a bounding box

Today, just say object-fit: contain. Support is everything but IE: http://caniuse.com/#feat=object-fit

Issue when importing dataset: `Error in scan(...): line 1 did not have 145 elements`

Beside all the guidance mentioned above,you can also check all the data.

If there are blanks between words, you must replace them with "_".

However that how I solve my own problem.

How to get to a particular element in a List in java?

String[] is an array of Strings. Such an array is internally a class. Like all classes that don't explicitly extend some other class, it extends Object implicitly. The method toString() of class Object, by default, gives you the representation you see: the class name, followed by @, followed by the hash code in hex. Since the String[] class doesn't override the toString() method, you get that as a result.

Create some method that outputs the array elements for you. Iterate over the array and use System.out.print() (not print*ln*) on the elements.

Calling a JavaScript function named in a variable

I'd avoid eval.

To solve this problem, you should know these things about JavaScript.

  1. Functions are first-class objects, so they can be properties of an object (in which case they are called methods) or even elements of arrays.
  2. If you aren't choosing the object a function belongs to, it belongs to the global scope. In the browser, that means you're hanging it on the object named "window," which is where globals live.
  3. Arrays and objects are intimately related. (Rumor is they might even be the result of incest!) You can often substitute using a dot . rather than square brackets [], or vice versa.

Your problem is a result of considering the dot manner of reference rather than the square bracket manner.

So, why not something like,

window["functionName"]();

That's assuming your function lives in the global space. If you've namespaced, then:

myNameSpace["functionName"]();

Avoid eval, and avoid passing a string in to setTimeout and setInterval. I write a lot of JS, and I NEVER need eval. "Needing" eval comes from not knowing the language deeply enough. You need to learn about scoping, context, and syntax. If you're ever stuck with an eval, just ask--you'll learn quickly.

Notepad++ - How can I replace blank lines

You can record a macro that removes the first blank line, and positions the cursor correctly for the second line. Then you can repeat executing that macro.

Check if DataRow exists by column name in c#?

if (drMyRow.Table.Columns["ColNameToCheck"] != null)
{
   doSomethingUseful;
{
else { return; }

Although the DataRow does not have a Columns property, it does have a Table that the column can be checked for.

Specify path to node_modules in package.json

yes you can, just set the NODE_PATH env variable :

export NODE_PATH='yourdir'/node_modules

According to the doc :

If the NODE_PATH environment variable is set to a colon-delimited list of absolute paths, then node will search those paths for modules if they are not found elsewhere. (Note: On Windows, NODE_PATH is delimited by semicolons instead of colons.)

Additionally, node will search in the following locations:

1: $HOME/.node_modules

2: $HOME/.node_libraries

3: $PREFIX/lib/node

Where $HOME is the user's home directory, and $PREFIX is node's configured node_prefix.

These are mostly for historic reasons. You are highly encouraged to place your dependencies locally in node_modules folders. They will be loaded faster, and more reliably.

Source

How to check whether a Button is clicked by using JavaScript

Just hook up the onclick event:

<input id="button" type="submit" name="button" value="enter" onclick="myFunction();"/>

Could not load file or assembly 'Newtonsoft.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies

I made a basic Demo and reproduced this problem. It seems that WinRT component failed to find the correct assembly of Newton.Json. Temporarily the workaround is to manually add the Newtonsoft.json.dll file. You can achieve this by following steps:

  1. Right click References-> Add Reference->Browse...-> Find C:\Users\.nuget\packages\Newtonsoft.Json\9.0.1\lib\portable-net45+wp80+win8+wpa81\Newtonsoft.json.dll->Click Add button.

  2. Rebuild your Runtime Component project and run. This error should be gone.

How to use Elasticsearch with MongoDB?

This answer should be enough to get you set up to follow this tutorial on Building a functional search component with MongoDB, Elasticsearch, and AngularJS.

If you're looking to use faceted search with data from an API then Matthiasn's BirdWatch Repo is something you might want to look at.

So here's how you can setup a single node Elasticsearch "cluster" to index MongoDB for use in a NodeJS, Express app on a fresh EC2 Ubuntu 14.04 instance.

Make sure everything is up to date.

sudo apt-get update

Install NodeJS.

sudo apt-get install nodejs
sudo apt-get install npm

Install MongoDB - These steps are straight from MongoDB docs. Choose whatever version you're comfortable with. I'm sticking with v2.4.9 because it seems to be the most recent version MongoDB-River supports without issues.

Import the MongoDB public GPG Key.

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10

Update your sources list.

echo 'deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen' | sudo tee /etc/apt/sources.list.d/mongodb.list

Get the 10gen package.

sudo apt-get install mongodb-10gen

Then pick your version if you don't want the most recent. If you are setting your environment up on a windows 7 or 8 machine stay away from v2.6 until they work some bugs out with running it as a service.

apt-get install mongodb-10gen=2.4.9

Prevent the version of your MongoDB installation being bumped up when you update.

echo "mongodb-10gen hold" | sudo dpkg --set-selections

Start the MongoDB service.

sudo service mongodb start

Your database files default to /var/lib/mongo and your log files to /var/log/mongo.

Create a database through the mongo shell and push some dummy data into it.

mongo YOUR_DATABASE_NAME
db.createCollection(YOUR_COLLECTION_NAME)
for (var i = 1; i <= 25; i++) db.YOUR_COLLECTION_NAME.insert( { x : i } )

Now to Convert the standalone MongoDB into a Replica Set.

First Shutdown the process.

mongo YOUR_DATABASE_NAME
use admin
db.shutdownServer()

Now we're running MongoDB as a service, so we don't pass in the "--replSet rs0" option in the command line argument when we restart the mongod process. Instead, we put it in the mongod.conf file.

vi /etc/mongod.conf

Add these lines, subbing for your db and log paths.

replSet=rs0
dbpath=YOUR_PATH_TO_DATA/DB
logpath=YOUR_PATH_TO_LOG/MONGO.LOG

Now open up the mongo shell again to initialize the replica set.

mongo DATABASE_NAME
config = { "_id" : "rs0", "members" : [ { "_id" : 0, "host" : "127.0.0.1:27017" } ] }
rs.initiate(config)
rs.slaveOk() // allows read operations to run on secondary members.

Now install Elasticsearch. I'm just following this helpful Gist.

Make sure Java is installed.

sudo apt-get install openjdk-7-jre-headless -y

Stick with v1.1.x for now until the Mongo-River plugin bug gets fixed in v1.2.1.

wget https://download.elasticsearch.org/elasticsearch/elasticsearch/elasticsearch-1.1.1.deb
sudo dpkg -i elasticsearch-1.1.1.deb

curl -L http://github.com/elasticsearch/elasticsearch-servicewrapper/tarball/master | tar -xz
sudo mv *servicewrapper*/service /usr/local/share/elasticsearch/bin/
sudo rm -Rf *servicewrapper*
sudo /usr/local/share/elasticsearch/bin/service/elasticsearch install
sudo ln -s `readlink -f /usr/local/share/elasticsearch/bin/service/elasticsearch` /usr/local/bin/rcelasticsearch

Make sure /etc/elasticsearch/elasticsearch.yml has the following config options enabled if you're only developing on a single node for now:

cluster.name: "MY_CLUSTER_NAME"
node.local: true

Start the Elasticsearch service.

sudo service elasticsearch start

Verify it's working.

curl http://localhost:9200

If you see something like this then you're good.

{
  "status" : 200,
  "name" : "Chi Demon",
  "version" : {
    "number" : "1.1.2",
    "build_hash" : "e511f7b28b77c4d99175905fac65bffbf4c80cf7",
    "build_timestamp" : "2014-05-22T12:27:39Z",
    "build_snapshot" : false,
    "lucene_version" : "4.7"
  },
  "tagline" : "You Know, for Search"
}

Now install the Elasticsearch plugins so it can play with MongoDB.

bin/plugin --install com.github.richardwilly98.elasticsearch/elasticsearch-river-mongodb/1.6.0
bin/plugin --install elasticsearch/elasticsearch-mapper-attachments/1.6.0

These two plugins aren't necessary but they're good for testing queries and visualizing changes to your indexes.

bin/plugin --install mobz/elasticsearch-head
bin/plugin --install lukas-vlcek/bigdesk

Restart Elasticsearch.

sudo service elasticsearch restart

Finally index a collection from MongoDB.

curl -XPUT localhost:9200/_river/DATABASE_NAME/_meta -d '{
  "type": "mongodb",
  "mongodb": {
    "servers": [
      { "host": "127.0.0.1", "port": 27017 }
    ],
    "db": "DATABASE_NAME",
    "collection": "ACTUAL_COLLECTION_NAME",
    "options": { "secondary_read_preference": true },
    "gridfs": false
  },
  "index": {
    "name": "ARBITRARY INDEX NAME",
    "type": "ARBITRARY TYPE NAME"
  }
}'

Check that your index is in Elasticsearch

curl -XGET http://localhost:9200/_aliases

Check your cluster health.

curl -XGET 'http://localhost:9200/_cluster/health?pretty=true'

It's probably yellow with some unassigned shards. We have to tell Elasticsearch what we want to work with.

curl -XPUT 'localhost:9200/_settings' -d '{ "index" : { "number_of_replicas" : 0 } }'

Check cluster health again. It should be green now.

curl -XGET 'http://localhost:9200/_cluster/health?pretty=true'

Go play.

REST API Login Pattern

Principled Design of the Modern Web Architecture by Roy T. Fielding and Richard N. Taylor, i.e. sequence of works from all REST terminology came from, contains definition of client-server interaction:

All REST interactions are stateless. That is, each request contains all of the information necessary for a connector to understand the request, independent of any requests that may have preceded it.

This restriction accomplishes four functions, 1st and 3rd are important in this particular case:

  • 1st: it removes any need for the connectors to retain application state between requests, thus reducing consumption of physical resources and improving scalability;
  • 3rd: it allows an intermediary to view and understand a request in isolation, which may be necessary when services are dynamically rearranged;

And now lets go back to your security case. Every single request should contains all required information, and authorization/authentication is not an exception. How to achieve this? Literally send all required information over wires with every request.

One of examples how to archeive this is hash-based message authentication code or HMAC. In practice this means adding a hash code of current message to every request. Hash code calculated by cryptographic hash function in combination with a secret cryptographic key. Cryptographic hash function is either predefined or part of code-on-demand REST conception (for example JavaScript). Secret cryptographic key should be provided by server to client as resource, and client uses it to calculate hash code for every request.

There are a lot of examples of HMAC implementations, but I'd like you to pay attention to the following three:

How it works in practice

If client knows the secret key, then it's ready to operate with resources. Otherwise he will be temporarily redirected (status code 307 Temporary Redirect) to authorize and to get secret key, and then redirected back to the original resource. In this case there is no need to know beforehand (i.e. hardcode somewhere) what the URL to authorize the client is, and it possible to adjust this schema with time.

Hope this will helps you to find the proper solution!

axios post request to send form data

You can post axios data by using FormData() like:

var bodyFormData = new FormData();

And then add the fields to the form you want to send:

bodyFormData.append('userName', 'Fred');

If you are uploading images, you may want to use .append

bodyFormData.append('image', imageFile); 

And then you can use axios post method (You can amend it accordingly)

axios({
  method: "post",
  url: "myurl",
  data: bodyFormData,
  headers: { "Content-Type": "multipart/form-data" },
})
  .then(function (response) {
    //handle success
    console.log(response);
  })
  .catch(function (response) {
    //handle error
    console.log(response);
  });

Related GitHub issue:

Can't get a .post with 'Content-Type': 'multipart/form-data' to work @ axios/axios

Need to make a clickable <div> button

Just use an <a> by itself, set it to display: block; and set width and height. Get rid of the <span> and <div>. This is the semantic way to do it. There is no need to wrap things in <divs> (or any element) for layout. That is what CSS is for.

Demo: http://jsfiddle.net/ThinkingStiff/89Enq/

HTML:

<a id="music" href="Music.html">Music I Like</a>

CSS:

#music {
    background-color: black;
    color: white;
    display: block;
    height: 40px;
    line-height: 40px;
    text-decoration: none;
    width: 100px;
    text-align: center;
}

Output:

enter image description here

Keep overflow div scrolled to bottom unless user scrolls up

I was able to get this working with CSS only.

The trick is to use display: flex; and flex-direction: column-reverse;

The browser treats the bottom like its the top. Assuming the browsers you're targeting support flex-box, the only caveat is that the markup has to be in reverse order.

Here is a working example. https://codepen.io/jimbol/pen/YVJzBg

NOW() function in PHP

I like the solution posted by user1786647, and I've updated it a little to change the timezone to a function argument and add optional support for passing either a Unix time or datetime string to use for the returned datestamp.

It also includes a fallback for "setTimestamp" for users running version lower than PHP 5.3:

function DateStamp($strDateTime = null, $strTimeZone = "Europe/London") {
    $objTimeZone = new DateTimeZone($strTimeZone);

    $objDateTime = new DateTime();
    $objDateTime->setTimezone($objTimeZone);

    if (!empty($strDateTime)) {
        $fltUnixTime = (is_string($strDateTime)) ? strtotime($strDateTime) : $strDateTime;

        if (method_exists($objDateTime, "setTimestamp")) {
            $objDateTime->setTimestamp($fltUnixTime);
        }
        else {
            $arrDate = getdate($fltUnixTime);
            $objDateTime->setDate($arrDate['year'], $arrDate['mon'], $arrDate['mday']);
            $objDateTime->setTime($arrDate['hours'], $arrDate['minutes'], $arrDate['seconds']);
        }
    }
    return $objDateTime->format("Y-m-d H:i:s");
}

Is there a naming convention for git repositories?

Without favouring any particular naming choice, remember that a git repo can be cloned into any root directory of your choice:

git clone https://github.com/user/repo.git myDir

Here repo.git would be cloned into the myDir directory.

So even if your naming convention for a public repo ended up to be slightly incorrect, it would still be possible to fix it on the client side.

That is why, in a distributed environment where any client can do whatever he/she wants, there isn't really a naming convention for Git repo.
(except to reserve "xxx.git" for bare form of the repo 'xxx')
There might be naming convention for REST service (similar to "Are there any naming convention guidelines for REST APIs?"), but that is a separate issue.

Retrieve Button value with jQuery

As a button value is an attribute you need to use the .attr() method in jquery. This should do it

<script type="text/javascript">
    $(document).ready(function() {
        $('.my_button').click(function() {
            alert($(this).attr("value"));
        });
    });
</script>

You can also use attr to set attributes, more info in the docs.

This only works in JQuery 1.6+. See postpostmodern's answer for older versions.

jQuery - Appending a div to body, the body is the object?

var $div = $('<div />').appendTo('body');
$div.attr('id', 'holdy');

Qt c++ aggregate 'std::stringstream ss' has incomplete type and cannot be defined

Like it's written up there, you forget to type #include <sstream>

#include <sstream>
using namespace std;

QString Stats_Manager::convertInt(int num)
{
   stringstream ss;
   ss << num;
   return ss.str();
}

You can also use some other ways to convert int to string, like

char numstr[21]; // enough to hold all numbers up to 64-bits
sprintf(numstr, "%d", age);
result = name + numstr;

check this!

C# Return Different Types?

If there is no common base-type or interface, then public object GetAnything() {...} - but it would usually be preferable to have some kind of abstraction such as a common interface. For example if Hello, Computer and Radio all implemented IFoo, then it could return an IFoo.

Difference between Pragma and Cache-Control headers?

Pragma is the HTTP/1.0 implementation and cache-control is the HTTP/1.1 implementation of the same concept. They both are meant to prevent the client from caching the response. Older clients may not support HTTP/1.1 which is why that header is still in use.

Custom domain for GitHub project pages

I just discovered, after a bit of frustration, that if you're using PairNIC, all you have to do is enable the "Web Forwarding" setting under "Custom DNS" and supply the username.github.io/project address and it will automatically set up both the apex and subdomain records for you. It appears to do exactly what's suggested in the accepted answer. However, it won't let you do the exact same thing by manually adding records. Very strange. Anyway, it took me a while to figure that out, so I thought I'd share to save everyone else the trouble.