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Some Of The Best Answers From Latest Asked Questions

Create a directly-executable cross-platform GUI app using Python

For the GUI itself:

PyQT is pretty much the reference.

Another way to develop a rapid user interface is to write a web app, have it run locally and display the app in the browser.

Plus, if you go for the Tkinter option suggested by lubos hasko you may want to try portablepy to have your app run on Windows environment without Python.

Text Editor For Linux (Besides Vi)?

I agree with Mike, though I'm a Vim die-hard. I've been using GEdit quite frequently lately when I'm doing lightweight Ruby scripting. The standard editor (plus Ruby code snippets) is extremely usable and polished, and can provide a nice reprieve from full-strength, always-on programming editors.

Options for HTML scraping?

Scraping Stack Overflow is especially easy with Shoes and Hpricot.

require 'hpricot' :title => "Ask Stack Overflow", :width => 370 do
  SO_URL = ""
  stack do
    stack do
      caption "What is your question?"
      flow do
        @lookup = edit_line "stackoverflow", :width => "-115px"
        button "Ask", :width => "90px" do
          download SO_URL + "/search?s=" + @lookup.text do |s|
            doc = Hpricot(s.response.body)
            (doc/:a).each do |l|
              href = l["href"]
              if href.to_s =~ /\/questions\/[0-9]+/ then
                @rez.append do
                  para(link(l.inner_text) { visit(SO_URL + href) })
    stack :margin => 25 do
      background white, :radius => 20
      @rez = stack do

How do you format an unsigned long long int using printf?

%d--> for int

%u--> for unsigned int

%ld--> for long int or long

%lu--> for unsigned long int or long unsigned int or unsigned long

%lld--> for long long int or long long

%llu--> for unsigned long long int or unsigned long long

Recommended add-ons/plugins for Microsoft Visual Studio

JustDecompile from telerik. Now that Reflector is no longer free. Its a necessity when digging through supplied libraries.

How do I split a string so I can access item x?

Recursive CTE solution with server pain, test it

MS SQL Server 2008 Schema Setup:

create table Course( Courses varchar(100) );
insert into Course values ('Hello John Smith');

Query 1:

with cte as
   ( select 
        left( Courses, charindex( ' ' , Courses) ) as a_l,
        cast( substring( Courses, 
                         charindex( ' ' , Courses) + 1 , 
                         len(Courses ) ) + ' ' 
              as varchar(100) )  as a_r,
        Courses as a,
        0 as n
     from Course t
    union all
        left(a_r, charindex( ' ' , a_r) ) as a_l,
        substring( a_r, charindex( ' ' , a_r) + 1 , len(a_R ) ) as a_r,
        cte.n + 1 as n
    from Course t inner join cte 
         on t.Courses = cte.a and len( a_r ) > 0

select a_l, n from cte
--where N = 1


|    A_L | N |
| Hello  | 0 |
|  John  | 1 |
| Smith  | 2 |

How do you disable browser Autocomplete on web form field / input tag?

Adding the


to the form tag will disable the browser autocomplete (what was previously typed into that field) from all input fields within that particular form.

Tested on:

  • Firefox 3.5, 4 BETA
  • Internet Explorer 8
  • Chrome

.NET obfuscation tools/strategy

The short answer is that you can't.

There are various tools around that will make it harder for someone to read your code - some of which have been pointed out by other answers.

However, all these do is make it harder to read - they increase the amount of effort required, that is all. Often this is enough to deter casual readers, but someone who is determined to dig into your code will always be able to do so.

Auto Generate Database Diagram MySQL

The "Reverse Engineer Database" mode in Workbench is only part of the paid version, not the free one.

How can I remove duplicate rows?

    table_name T1
    rowid > (
            table_name T2
            T1.column_name = T2.column_name

How to find keys of a hash?

using jQuery you can get the keys like this:

var bobject =  {primary:"red",bg:"maroon",hilite:"green"};
var keys = [];
$.each(bobject, function(key,val){ keys.push(key); });
console.log(keys); // ["primary", "bg", "hilite"]


var bobject =  {primary:"red",bg:"maroon",hilite:"green"};
$.map(bobject, function(v,k){return k;});

thanks to @pimlottc

Random integer in VB.NET

Function xrand() As Long
        Dim r1 As Long = Now.Day & Now.Month & Now.Year & Now.Hour & Now.Minute & Now.Second & Now.Millisecond
        Dim RAND As Long = Math.Max(r1, r1 * 2)
        Return RAND
End Function

[BBOYSE] This its the best way, from scratch :P

Quick easy way to migrate SQLite3 to MySQL?

Get a SQL dump

moose@pc08$ sqlite3 mySqliteDatabase.db .dump > myTemporarySQLFile.sql

Import dump to MySQL

For small imports:

moose@pc08$ mysql -u <username> -p
Enter password:
mysql> use somedb;
Database changed
mysql> source myTemporarySQLFile.sql;


mysql -u root -p somedb < myTemporarySQLFile.sql

This will prompt you for a password. Please note: If you want to enter your password directly, you have to do it WITHOUT space, directly after -p:

mysql -u root -pYOURPASS somedb < myTemporarySQLFile.sql

For larger dumps:

mysqlimport or other import tools like BigDump.

BigDump gives you a progress bar:

enter image description here

How do you configure tomcat to bind to a single ip address (localhost) instead of all addresses?

It may be worth mentioning that running tomcat as a non root user (which you should be doing) will prevent you from using a port below 1024 on *nix. If you want to use TC as a standalone server -- as its performance no longer requires it to be fronted by Apache or the like -- you'll want to bind to port 80 along with whatever IP address you're specifying.

You can do this by using IPTABLES to redirect port 80 to 8080.

Converting List<Integer> to List<String>

Using Streams : If let say result is list of integers (List<Integer> result) then :

List<String> ids = (List<String>) -> Integer.toString(intNumber)).collect(Collectors.toList());

One of the ways to solve it. Hope this helps.

What are some good SSH Servers for windows?

I've been using Bitvise SSH Server and it's really great. From install to administration it does it all through a GUI so you won't be putting together a sshd_config file. Plus if you use their client, Tunnelier, you get some bonus features (like mapping shares, port forwarding setup up server side, etc.) If you don't use their client it will still work with the Open Source SSH clients.

It's not Open Source and it costs $39.95, but I think it's worth it.

UPDATE 2009-05-21 11:10: The pricing has changed. The current price is $99.95 per install for commercial, but now free for non-commercial/personal use. Here is the current pricing.

Validate decimal numbers in JavaScript - IsNumeric()

None of the answers return false for empty strings, a fix for that...

function is_numeric(n)
 return (n != '' && !isNaN(parseFloat(n)) && isFinite(n));

How to generate a core dump in Linux on a segmentation fault?

It's worth mentioning that if you have a systemd set up, then things are a little bit different. The set up typically would have the core files be piped, by means of core_pattern sysctl value, through systemd-coredump(8). The core file size rlimit would typically be configured as "unlimited" already.

It is then possible to retrieve the core dumps using coredumpctl(1).

The storage of core dumps, etc. is configured by coredump.conf(5). There are examples of how to get the core files in the coredumpctl man page, but in short, it would look like this:

Find the core file:

[vps@phoenix]~$ coredumpctl list test_me | tail -1
Sun 2019-01-20 11:17:33 CET   16163  1224  1224  11 present /home/vps/test_me

Get the core file:

[vps@phoenix]~$ coredumpctl -o test_me.core dump 16163

How to round up the result of integer division?

I do the following, handles any overflows:

var totalPages = totalResults.IsDivisble(recordsperpage) ? totalResults/(recordsperpage) : totalResults/(recordsperpage) + 1;

And use this extension for if there's 0 results:

public static bool IsDivisble(this int x, int n)
           return (x%n) == 0;

Also, for the current page number (wasn't asked but could be useful):

var currentPage = (int) Math.Ceiling(recordsperpage/(double) recordsperpage) + 1;

Warning: Found conflicts between different versions of the same dependent assembly

I had such issue when my project had reference to NETStandardLibrary and one of referenced assemblies was published for netcore. Just published it as netstandard and problem was gone

When should you use 'friend' in C++?

edit: Reading the faq a bit longer I like the idea of the << >> operator overloading and adding as a friend of those classes, however I am not sure how this doesn't break encapsulation

How would it break encapsulation?

You break encapsulation when you allow unrestricted access to a data member. Consider the following classes:

class c1 {
  int x;

class c2 {
  int foo();
  int x;

class c3 {
  friend int foo();
  int x;

c1 is obviously not encapsulated. Anyone can read and modify x in it. We have no way to enforce any kind of access control.

c2 is obviously encapsulated. There is no public access to x. All you can do is call the foo function, which performs some meaningful operation on the class.

c3? Is that less encapsulated? Does it allow unrestricted access to x? Does it allow unknown functions access?

No. It allows precisely one function to access the private members of the class. Just like c2 did. And just like c2, the one function which has access is not "some random, unknown function", but "the function listed in the class definition". Just like c2, we can see, just by looking at the class definitions, a complete list of who has access.

So how exactly is this less encapsulated? The same amount of code has access to the private members of the class. And everyone who has access is listed in the class definition.

friend does not break encapsulation. It makes some Java people programmers feel uncomfortable, because when they say "OOP", they actually mean "Java". When they say "Encapsulation", they don't mean "private members must be protected from arbitrary accesses", but "a Java class where the only functions able to access private members, are class members", even though this is complete nonsense for several reasons.

First, as already shown, it is too restricting. There's no reason why friend methods shouldn't be allowed to do the same.

Second, it is not restrictive enough. Consider a fourth class:

class c4 {
  int getx();
  void setx(int x);
  int x;

This, according to aforesaid Java mentality, is perfectly encapsulated. And yet, it allows absolutely anyone to read and modify x. How does that even make sense? (hint: It doesn't)

Bottom line: Encapsulation is about being able to control which functions can access private members. It is not about precisely where the definitions of these functions are located.

How do I send a file as an email attachment using Linux command line?

the shortest way for me is

file=filename_or_filepath;uuencode $file $file|mail -s "optional subject" email_address

so for your example it'll be

file=your_sql.log;gzip -c $file;uuencode ${file}.gz ${file}|mail -s "file with magnets" [email protected]

the good part is that I can recall it with Ctrl+r to send another file...

What is the most effective way for float and double comparison?

Found another interesting implementation on:

#include <cmath>
#include <limits>
#include <iomanip>
#include <iostream>
#include <type_traits>
#include <algorithm>

template<class T>
typename std::enable_if<!std::numeric_limits<T>::is_integer, bool>::type
    almost_equal(T x, T y, int ulp)
    // the machine epsilon has to be scaled to the magnitude of the values used
    // and multiplied by the desired precision in ULPs (units in the last place)
    return std::fabs(x-y) <= std::numeric_limits<T>::epsilon() * std::fabs(x+y) * ulp
        // unless the result is subnormal
        || std::fabs(x-y) < std::numeric_limits<T>::min();

int main()
    double d1 = 0.2;
    double d2 = 1 / std::sqrt(5) / std::sqrt(5);
    std::cout << std::fixed << std::setprecision(20) 
        << "d1=" << d1 << "\nd2=" << d2 << '\n';

    if(d1 == d2)
        std::cout << "d1 == d2\n";
        std::cout << "d1 != d2\n";

    if(almost_equal(d1, d2, 2))
        std::cout << "d1 almost equals d2\n";
        std::cout << "d1 does not almost equal d2\n";

When to use IList and when to use List

You should use the interface only if you need it, e.g., if your list is casted to an IList implementation other than List. This is true when, for example, you use NHibernate, which casts ILists into an NHibernate bag object when retrieving data.

If List is the only implementation that you will ever use for a certain collection, feel free to declare it as a concrete List implementation.

How to generate sample XML documents from their DTD or XSD?

XML Blueprint also does that; instructions here

It's not free, but there's a 10-day free trial; it seems fast and efficient; unfortunately it's Windows only.

What Ruby IDE do you prefer?

emacs with ruby-mode, rdebug and a ruby interactive inferior shell.

How to select the nth row in a SQL database table?

  SELECT TOP 1000 * FROM emp

This will give the 1000th row in SQL Server.

What is a lambda (function)?

In context of CS a lambda function is an abstract mathematical concept that tackles a problem of symbolic evaluation of mathematical expressions. In that context a lambda function is the same as a lambda term.

But in programming languages it's something different. It's a piece of code that is declared "in place", and that can be passed around as a "first-class citizen". This concept appeared to be useful so that it came into almost all popular modern programming languages (see lambda functions everwhere post).

How to redirect siteA to siteB with A or CNAME records

It sounds like the web server on doesn't allow undefined domains to be passed through. You also said you wanted to do a redirect, this isn't actually a method for redirecting. If you bought this domain through GoDaddy you may just want to use their redirection service.

What do "branch", "tag" and "trunk" mean in Subversion repositories?

In addition to what Nick has said you can find out more at Streamed Lines: Branching Patterns for Parallel Software Development

enter image description here

In this figure main is the trunk, rel1-maint is a branch and 1.0 is a tag.

Convert a string to an enum in C#

Use Enum.TryParse<T>(String, T) (= .NET 4.0):

StatusEnum myStatus;
Enum.TryParse("Active", out myStatus);

It can be simplified even further with C# 7.0's parameter type inlining:

Enum.TryParse("Active", out StatusEnum myStatus);

How do I convert a file path to a URL in ASP.NET

Maybe this is not the best way, but it works.

// Here is your path
String p = photosLocation + "whatever.jpg";

// Here is the page address
String pa = Page.Request.Url.AbsoluteUri;

// Take the page name    
String pn = Page.Request.Url.LocalPath;

// Here is the server address    
String sa = pa.Replace(pn, "");

// Take the physical location of the page    
String pl = Page.Request.PhysicalPath;

// Replace the backslash with slash in your path    
pl = pl.Replace("\\", "/");    
p = p.Replace("\\", "/");

// Root path     
String rp = pl.Replace(pn, "");

// Take out same path    
String final = p.Replace(rp, "");

// So your picture's address is    
String path = sa + final;

Edit: Ok, somebody marked as not helpful. Some explanation: take the physical path of the current page, split it into two parts: server and directory (like c:\inetpub\\whatever) and page name (like /Whatever.aspx). The image's physical path should contain the server's path, so "substract" them, leaving only the image's path relative to the server's (like: \design\picture.jpg). Replace the backslashes with slashes and append it to the server's url.

Reading Excel files from C#

You can try using this open source solution that makes dealing with Excel a lot more cleaner.

Changing the resolution of a VNC session in linux

Adding to Nathan's (accepted) answer:

I wanted to cycle through the list of resolutions but didnt see anything for it:

function vncNextRes()
   xrandr -s $(($(xrandr | grep '^*'|sed 's@^\*\([0-9]*\).*$@\1@')+1)) > /dev/null 2>&1 || \
   xrandr -s 0

It gets the current index, steps to the next one and cycles back to 0 on error (i.e. end)


Modified to match a later version of xrandr ("*" is on end of line and no leading resolution identifier).

function vncNextRes()
   xrandr -s $(($(xrandr 2>/dev/null | grep -n '\* *$'| sed 's@:.*@@')-2))  || \
   xrandr -s 0

What's the best way to validate an XML file against an XSD file?

Using Woodstox, configure the StAX parser to validate against your schema and parse the XML.

If exceptions are caught the XML is not valid, otherwise it is valid:

// create the XSD schema from your schema file
XMLValidationSchemaFactory schemaFactory = XMLValidationSchemaFactory.newInstance(XMLValidationSchema.SCHEMA_ID_W3C_SCHEMA);
XMLValidationSchema validationSchema = schemaFactory.createSchema(schemaInputStream);

// create the XML reader for your XML file
WstxInputFactory inputFactory = new WstxInputFactory();
XMLStreamReader2 xmlReader = (XMLStreamReader2) inputFactory.createXMLStreamReader(xmlInputStream);

try {
    // configure the reader to validate against the schema

    // parse the XML
    while (xmlReader.hasNext()) {;

    // no exceptions, the XML is valid

} catch (XMLStreamException e) {

    // exceptions, the XML is not valid

} finally {

Note: If you need to validate multiple files, you should try to reuse your XMLInputFactory and XMLValidationSchema in order to maximize the performance.

How can I determine whether a specific file is open in Windows?

The equivalent of lsof -p pid is the combined output from sysinternals handle and listdlls, ie

handle -p pid
listdlls -p pid

you can find out pid with sysinternals pslist.

Hidden Features of Java

Functors are pretty cool. They are pretty close to a function pointer, which everyone is usually quick to say is impossible in Java.

Functors in Java

Sorting an IList in C#

Here's an example using the stronger typing. Not sure if it's necessarily the best way though.

static void Main(string[] args)
    IList list = new List<int>() { 1, 3, 2, 5, 4, 6, 9, 8, 7 };
    List<int> stronglyTypedList = new List<int>(Cast<int>(list));

private static IEnumerable<T> Cast<T>(IEnumerable list)
    foreach (T item in list)
        yield return item;

The Cast function is just a reimplementation of the extension method that comes with 3.5 written as a normal static method. It is quite ugly and verbose unfortunately.

How to change the icon of .bat file programmatically?

try with shortcutjs.bat to create a shortcut:

call shortcutjs.bat -linkfile mybat3.lnk -target "%cd%\Ascii2All.bat" -iconlocation "%SystemRoot%\System32\SHELL32.dll,77"

you can use the -iconlocation switch to point to a icon .

What's the best UML diagramming tool?


I used this for my thesis and it is well-designed: maybe it has too much feature not very important but I prefer have some uselee feature than don't have some useful feature.

How to retrieve a file from a server via SFTP?

JSch library is the powerful library that can be used to read file from SFTP server. Below is the tested code to read file from SFTP location line by line

JSch jsch = new JSch();
        Session session = null;
        try {
            session = jsch.getSession("user", "", 22);
            session.setConfig("StrictHostKeyChecking", "no");

            Channel channel = session.openChannel("sftp");
            ChannelSftp sftpChannel = (ChannelSftp) channel;

            InputStream stream = sftpChannel.get("/usr/home/testfile.txt");
            try {
                BufferedReader br = new BufferedReader(new InputStreamReader(stream));
                String line;
                while ((line = br.readLine()) != null) {

            } catch (IOException io) {
                System.out.println("Exception occurred during reading file from SFTP server due to " + io.getMessage());

            } catch (Exception e) {
                System.out.println("Exception occurred during reading file from SFTP server due to " + e.getMessage());


        } catch (JSchException e) {
        } catch (SftpException e) {

Please refer the blog for whole program.

LINQ-to-SQL vs stored procedures?

Stored procedure makes testing easier and you can change the query without touching the application code. Also with linq, getting a data does not mean its the right data. And testing the correctness of the data means running the application but with stored procedure it's easy to test without touching the application.

fopen deprecated warning

Consider using a portability library like glib or the apache portable runtime. These usually provide safe, portable alternatives to calls like these. It's a good thing too, because these insecure calls are deprecated in most modern environments.

How can I remove a child node in HTML using JavaScript?

Use the following code:

//for Internet Explorer

//for other browsers
var fDiv = document.getElementById("FirstDiv");
fDiv.removeChild(fDiv.childNodes[0]); //first check on which node your required node exists, if it is on [0] use this, otherwise use where it exists.

How can I permanently enable line numbers in IntelliJ?

On Mac Intellij 12.1.2 there is no File-Settings:

There is an application-name menu item to the left of "File" with a "preferences" menu item:

Choosing "Preferences" on the Mac.

and within that is the "Settings" dialog shown by the Windows Intellij.

mysqli or PDO - what are the pros and cons?

PDO is the standard, it's what most developers will expect to use. mysqli was essentially a bespoke solution to a particular problem, but it has all the problems of the other DBMS-specific libraries. PDO is where all the hard work and clever thinking will go.

What's the difference between struct and class in .NET?

A short summary of each:

Classes Only:

  • Can support inheritance
  • Are reference (pointer) types
  • The reference can be null
  • Have memory overhead per new instance

Structs Only:

  • Cannot support inheritance
  • Are value types
  • Are passed by value (like integers)
  • Cannot have a null reference (unless Nullable is used)
  • Do not have a memory overhead per new instance - unless 'boxed'

Both Classes and Structs:

  • Are compound data types typically used to contain a few variables that have some logical relationship
  • Can contain methods and events
  • Can support interfaces

Mercurial stuck "waiting for lock"

If it only happens on mapped drives it might be bug Using UNC path instead of drive letter seems to sidestep the issue.

How do I tell if a variable has a numeric value in Perl?

Usually number validation is done with regular expressions. This code will determine if something is numeric as well as check for undefined variables as to not throw warnings:

sub is_integer {
   defined $_[0] && $_[0] =~ /^[+-]?\d+$/;

sub is_float {
   defined $_[0] && $_[0] =~ /^[+-]?\d+(\.\d+)?$/;

Here's some reading material you should look at.

What is the easiest way to parse an INI File in C++?

Unless you plan on making the app cross-platform, using the Windows API calls would be the best way to go. Just ignore the note in the API documentation about being provided only for 16-bit app compatibility.

How do you get a directory listing in C?

The strict answer is "you can't", as the very concept of a folder is not truly cross-platform.

On MS platforms you can use _findfirst, _findnext and _findclose for a 'c' sort of feel, and FindFirstFile and FindNextFile for the underlying Win32 calls.

Here's the C-FAQ answer:

How should I unit test multithreaded code?

You may use EasyMock.makeThreadSafe to make testing instance threadsafe

Calling the base constructor in C#

Using newer C# features, namely out var, you can get rid of the static factory-method. I just found out (by accident) that out var parameter of methods called inse base-"call" flow to the constructor body.

Example, using this base class you want to derive from:

public abstract class BaseClass
    protected BaseClass(int a, int b, int c)

The non-compiling pseudo code you want to execute:

public class DerivedClass : BaseClass
    private readonly object fatData;

    public DerivedClass(int m)
        var fd = new { A = 1 * m, B = 2 * m, C = 3 * m };
        base(fd.A, fd.B, fd.C); // base-constructor call
        this.fatData = fd;

And the solution by using a static private helper method which produces all required base arguments (plus additional data if needed) and without using a static factory method, just plain constructor to the outside:

public class DerivedClass : BaseClass
    private readonly object fatData;

    public DerivedClass(int m)
        : base(PrepareBaseParameters(m, out var b, out var c, out var fatData), b, c)
        this.fatData = fatData;
        Console.WriteLine(new { b, c, fatData }.ToString());

    private static int PrepareBaseParameters(int m, out int b, out int c, out object fatData)
        var fd = new { A = 1 * m, B = 2 * m, C = 3 * m };
        (b, c, fatData) = (fd.B, fd.C, fd); // Tuples not required but nice to use
        return fd.A;

Browse for a directory in C#

Please don't try and roll your own with a TreeView/DirectoryInfo class. For one thing there are many nice features you get for free (icons/right-click/networks) by using SHBrowseForFolder. For another there are a edge cases/catches you will likely not be aware of.

Case-insensitive string comparison in C++

boost::iequals is not utf-8 compatible in the case of string. You can use boost::locale.

comparator<char,collator_base::secondary> cmpr;
cout << (cmpr(str1, str2) ? "str1 < str2" : "str1 >= str2") << endl;
  • Primary -- ignore accents and character case, comparing base letters only. For example "facade" and "Façade" are the same.
  • Secondary -- ignore character case but consider accents. "facade" and "façade" are different but "Façade" and "façade" are the same.
  • Tertiary -- consider both case and accents: "Façade" and "façade" are different. Ignore punctuation.
  • Quaternary -- consider all case, accents, and punctuation. The words must be identical in terms of Unicode representation.
  • Identical -- as quaternary, but compare code points as well.

How do you kill all current connections to a SQL Server 2005 database?

Take offline takes a while and sometimes I experience some problems with that..

Most solid way in my opinion:

Detach Right click DB -> Tasks -> Detach... check "Drop Connections" Ok

Reattach Right click Databases -> Attach.. Add... -> select your database, and change the Attach As column to your desired database name. Ok

How to parse XML using vba

You can use a XPath Query:

Dim objDom As Object        '// DOMDocument
Dim xmlStr As String, _
    xPath As String

xmlStr = _
    "<PointN xsi:type='typens:PointN' " & _
    "xmlns:xsi='' " & _
    "xmlns:xs=''> " & _
    "    <X>24.365</X> " & _
    "    <Y>78.63</Y> " & _

Set objDom = CreateObject("Msxml2.DOMDocument.3.0")     '// Using MSXML 3.0

'/* Load XML */
objDom.LoadXML xmlStr

' * XPath Query
' */        

'/* Get X */
xPath = "/PointN/X"
Debug.Print objDom.SelectSingleNode(xPath).text

'/* Get Y */
xPath = "/PointN/Y"
Debug.Print objDom.SelectSingleNode(xPath).text

Refresh Excel VBA Function Results

This refreshes the calculation better than Range(A:B).Calculate:

Public Sub UpdateMyFunctions()
    Dim myRange As Range
    Dim rng As Range

    ' Assume the functions are in this range A1:B10.
    Set myRange = ActiveSheet.Range("A1:B10")

    For Each rng In myRange
        rng.Formula = rng.Formula
End Sub

What are the proper permissions for an upload folder with PHP/Apache?

I would support the idea of creating a ftp group that will have the rights to upload. However, i don't think it is necessary to give 775 permission. 7 stands for read, write, execute. Normally you want to allow certain groups to read and write, but depending on the case, execute may not be necessary.

How can you customize the numbers in an ordered list?

I suggest playing with the :before attribute and seeing what you can achieve with it. It will mean your code really is limited to nice new browsers, and excludes the (annoyingly large) section of the market still using rubbish old browsers,

Something like the following, which forces a fixed with on the items. Yes, I know it's less elegant to have to choose the width yourself, but using CSS for your layout is like undercover police work: however good your motives, it always gets messy.

li:before {
  content: counter(item) ") ";
  counter-increment: item;
  display: marker;
  width: 2em;

But you're going to have to experiment to find the exact solution.

LINQ query on a DataTable

This is a simple way that works for me and uses lambda expressions:

var results = myDataTable.Select("").FirstOrDefault(x => (int)x["RowNo"] == 1)

Then if you want a particular value:

if(results != null) 
    var foo = results["ColName"].ToString()

How to programmatically send SMS on the iPhone?

Add the MessageUI.Framework and use the following code

#import <MessageUI/MessageUI.h> 

And then:

if ([MFMessageComposeViewController canSendText]) {
  MFMessageComposeViewController *messageComposer =
  [[MFMessageComposeViewController alloc] init];
  NSString *message = @"Your Message here";
  [messageComposer setBody:message];
  messageComposer.messageComposeDelegate = self;
  [self presentViewController:messageComposer animated:YES completion:nil];

and the delegate method -

- (void)messageComposeViewController:(MFMessageComposeViewController *)controller
             didFinishWithResult:(MessageComposeResult)result {
      [self dismissViewControllerAnimated:YES completion:nil];

Compare a date string to datetime in SQL Server?

Date can be compared in sqlserver using string comparision: e.g.

SET @strDate ='07-12-2010'

WHERE CONVERT(VARCHAR(15),dtInvoice, 112)>= CONVERT(VARCHAR(15),@strDate , 112)

Why are my PowerShell scripts not running?

On Windows 10: Click change security property of myfile.ps1 and change "allow access" by right click / properties on myfile.ps1

Differences between MySQL and SQL Server

@Cebjyre. The IDE whether Enterprise Manager or Management Studio is better than anything I have seen so far for MySQL. I say 'easier to use' because I can do many things in MSSQL where MySQL has no counterparts. In MySQL I have no idea how to tune the queries by simply looking at the query plan or looking at the statistics. The index tuning wizard in MSSQL takes most of the guess work on what indexes are missing or misplaced.

One shortcoming of MySQL is there's no max size for a database. The database would just increase in size till it fills up the disk. Imagine if this disk is sharing databases with other users and suddenly all of their queries are failing because their databases can't grow. I have reported this issue to MySQL long time ago. I don't think it's fixed yet.

How can I set up an editor to work with Git on Windows?

For Atom you can do

git config --global core.editor "atom --wait"

and similar for Visual Studio Code

git config --global core.editor "code --wait"

which will open up an Atom or Visual Studio Code window for you to commit through,

or for Sublime Text:

git config --global core.editor "subl -n -w"

Oracle - What TNS Names file am I using?

Oracle provides a utility called tnsping:

R:\>tnsping someconnection

TNS Ping Utility for 32-bit Windows: Version - Production on 27-AUG-20
08 10:38:07

Copyright (c) 1997 Oracle Corporation.  All rights reserved.

Used parameter files:

TNS-03505: Failed to resolve name


R:\>tnsping entpr01

TNS Ping Utility for 32-bit Windows: Version - Production on 27-AUG-20
08 10:39:22

Copyright (c) 1997 Oracle Corporation.  All rights reserved.

Used parameter files:

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (COMMUNITY = **)
 (PROTOCOL = TCP) (Host = ****) (Port = 1521))) (CONNECT_DATA = (SID = ENTPR0
OK (40 msec)


This should show what file you're using. The utility sits in the Oracle bin directory.

Convert a hexadecimal string to an integer efficiently in C?

Edit: Now compatible with MSVC, C++ and non-GNU compilers (see end).

The question was "most efficient way." The OP doesn't specify platform, he could be compiling for a RISC based ATMEL chip with 256 bytes of flash storage for his code.

For the record, and for those (like me), who appreciate the difference between "the easiest way" and the "most efficient way", and who enjoy learning...

static const long hextable[] = {
   [0 ... 255] = -1, // bit aligned access into this table is considerably
   ['0'] = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, // faster for most modern processors,
   ['A'] = 10, 11, 12, 13, 14, 15,       // for the space conscious, reduce to
   ['a'] = 10, 11, 12, 13, 14, 15        // signed char.

 * @brief convert a hexidecimal string to a signed long
 * will not produce or process negative numbers except 
 * to signal error.
 * @param hex without decoration, case insensitive. 
 * @return -1 on error, or result (max (sizeof(long)*8)-1 bits)
long hexdec(unsigned const char *hex) {
   long ret = 0; 
   while (*hex && ret >= 0) {
      ret = (ret << 4) | hextable[*hex++];
   return ret; 

It requires no external libraries, and it should be blindingly fast. It handles uppercase, lowercase, invalid characters, odd-sized hex input (eg: 0xfff), and the maximum size is limited only by the compiler.

For non-GCC or C++ compilers or compilers that will not accept the fancy hextable declaration.

Replace the first statement with this (longer, but more conforming) version:

static const long hextable[] = { 
    -1,-1, 0,1,2,3,4,5,6,7,8,9,-1,-1,-1,-1,-1,-1,-1,10,11,12,13,14,15,-1,

How do I create a Linked List Data Structure in Java?

Use java.util.LinkedList. Like this:

list = new java.util.LinkedList()

How do I remove duplicates from a C# array?

NOTE : NOT tested!

string[] test(string[] myStringArray)
    List<String> myStringList = new List<string>();
    foreach (string s in myStringArray)
        if (!myStringList.Contains(s))
    return myStringList.ToString();

Might do what you need...

EDIT Argh!!! beaten to it by rob by under a minute!

How do you pass a function as a parameter in C?


A prototype for a function which takes a function parameter looks like the following:

void func ( void (*f)(int) );

This states that the parameter f will be a pointer to a function which has a void return type and which takes a single int parameter. The following function (print) is an example of a function which could be passed to func as a parameter because it is the proper type:

void print ( int x ) {
  printf("%d\n", x);

Function Call

When calling a function with a function parameter, the value passed must be a pointer to a function. Use the function's name (without parentheses) for this:


would call func, passing the print function to it.

Function Body

As with any parameter, func can now use the parameter's name in the function body to access the value of the parameter. Let's say that func will apply the function it is passed to the numbers 0-4. Consider, first, what the loop would look like to call print directly:

for ( int ctr = 0 ; ctr < 5 ; ctr++ ) {

Since func's parameter declaration says that f is the name for a pointer to the desired function, we recall first that if f is a pointer then *f is the thing that f points to (i.e. the function print in this case). As a result, just replace every occurrence of print in the loop above with *f:

void func ( void (*f)(int) ) {
  for ( int ctr = 0 ; ctr < 5 ; ctr++ ) {


How do you create a static class in C++?

In Managed C++, static class syntax is:-

public ref class BitParser abstract sealed
        static bool GetBitAt(...)

... better late than never...

Removing elements with in JavaScript

I just wrote array intersection that correctly handles also duplicates

// array intersection that correctly handles also duplicates_x000D_
const intersection = (a1, a2) => {_x000D_
  const cnt = new Map();_x000D_ => cnt[el] = el in cnt ? cnt[el] + 1 : 1);_x000D_
  return a1.filter(el => el in cnt && 0 < cnt[el]--);_x000D_
const l = console.log;_x000D_
l(intersection('1234'.split``, '3456'.split``)); // [ '3', '4' ]_x000D_
l(intersection('12344'.split``, '3456'.split``)); // [ '3', '4' ]_x000D_
l(intersection('1234'.split``, '33456'.split``)); // [ '3', '4' ]_x000D_
l(intersection('12334'.split``, '33456'.split``)); // [ '3', '3', '4' ]

Select all columns except one in MySQL?

Would a View work better in this case?

    , col2  
    , col3  
    , col..  
    , col53  
FROM table

grep a file, but show several surrounding lines?

You can use option -A (after) and -B (before) in your grep command try grep -nri -A 5 -B 5 .

Hidden Features of C#?

Nesting Using Statements

Usually we do it like this:

StringBuilder sb = new StringBuilder();
using (StringWriter sw = new StringWriter()) {
    using (IndentedTextWriter itw = new IndentedTextWriter(sw)) {

But we can do it this way:

StringBuilder sb = new StringBuilder();
using (StringWriter sw = new StringWriter())
using (IndentedTextWriter itw = new IndentedTextWriter(sw)) {

Storing a file in a database as opposed to the file system?

We made the decision to store as varbinary for halfway expecting performance issues. I can say that we've been pleasantly surprised at how well it's worked out.

Accessing MP3 metadata with Python

I looked the above answers and found out that they are not good for my project because of licensing problems with GPL.

And I found out this: PyID3Lib, while that particular python binding release date is old, it uses the ID3Lib, which itself is up to date.

Notable to mention is that both are LGPL, and are good to go.

Best implementation for Key Value Pair Data Structure?

@Jay Mooney: A generic Dictionary class in .NET is actually a hash table, just with fixed types.

The code you've shown shouldn't convince anyone to use Hashtable instead of Dictionary, since both code pieces can be used for both types.

For hashtable:

foreach(object key in h.keys)
     string keyAsString = key.ToString(); // btw, this is unnecessary
     string valAsString = h[key].ToString();

     System.Diagnostics.Debug.WriteLine(keyAsString + " " + valAsString);

For dictionary:

foreach(string key in d.keys)
     string valAsString = d[key].ToString();

     System.Diagnostics.Debug.WriteLine(key + " " + valAsString);

And just the same for the other one with KeyValuePair, just use the non-generic version for Hashtable, and the generic version for Dictionary.

So it's just as easy both ways, but Hashtable uses Object for both key and value, which means you will box all value types, and you don't have type safety, and Dictionary uses generic types and is thus better.

How to use XPath in Python?

Another library is 4Suite:

I do not know how spec-compliant it is. But it has worked very well for my use. It looks abandoned.

Entity Framework vs LINQ to SQL

I think if you need to develop something quick with no Strange things in the middle, and you need the facility to have entities representing your tables:

Linq2Sql can be a good allied, using it with LinQ unleashes a great developing timing.

Generic type conversion FROM string

Yet another variation. Handles Nullables, as well as situations where the string is null and T is not nullable.

public class TypedProperty<T> : Property where T : IConvertible
    public T TypedValue
            if (base.Value == null) return default(T);
            var type = Nullable.GetUnderlyingType(typeof(T)) ?? typeof(T);
            return (T)Convert.ChangeType(base.Value, type);
        set { base.Value = value.ToString(); }

Best way to access a control on another form in Windows Forms?

With the property (highlighted) I can get the instance of the MainForm class. But this is a good practice? What do you recommend?

For this I use the property MainFormInstance that runs on the OnLoad method.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using LightInfocon.Data.LightBaseProvider;
using System.Configuration;

namespace SINJRectifier

    public partial class MainForm : Form
        public MainForm()

        protected override void OnLoad(EventArgs e)
            UserInterface userInterfaceObj = new UserInterface();
            MainFormInstance.MainFormInstanceSet = this; //Here I get the instance

        private void btnBegin_Click(object sender, EventArgs e)

    static class MainFormInstance  //Here I get the instance
        private static MainForm mainFormInstance;

        public static MainForm MainFormInstanceSet { set { mainFormInstance = value; } }

        public static MainForm MainFormInstanceGet { get { return mainFormInstance; } }

What does the [Flags] Enum Attribute mean in C#?

You can also do this

public enum MyEnum
    None   = 0,
    First  = 1 << 0,
    Second = 1 << 1,
    Third  = 1 << 2,
    Fourth = 1 << 3

I find the bit-shifting easier than typing 4,8,16,32 and so on. It has no impact on your code because it's all done at compile time

100% Min Height CSS layout

I am using the following one: CSS Layout - 100 % height


The #container element of this page has a min-height of 100%. That way, if the content requires more height than the viewport provides, the height of #content forces #container to become longer as well. Possible columns in #content can then be visualised with a background image on #container; divs are not table cells, and you don't need (or want) the physical elements to create such a visual effect. If you're not yet convinced; think wobbly lines and gradients instead of straight lines and simple color schemes.

Relative positioning

Because #container has a relative position, #footer will always remain at its bottom; since the min-height mentioned above does not prevent #container from scaling, this will work even if (or rather especially when) #content forces #container to become longer.


Since it is no longer in the normal flow, padding-bottom of #content now provides the space for the absolute #footer. This padding is included in the scrolled height by default, so that the footer will never overlap the above content.

Scale the text size a bit or resize your browser window to test this layout.

html,body {
    height:100%; /* needed for container min-height */


h1 { 
    font:1.5em georgia,serif; 
    margin:0.5em 0;

h2 {
    font:1.25em georgia,serif; 
    margin:0 0 0.5em;
    h1, h2, a {

p { 
    margin:0 0 1em;

div#container {
    position:relative; /* needed for footer positioning*/
    margin:0 auto; /* center, not in IE5 */

    height:auto !important; /* real browsers */
    height:100%; /* IE6: treaded as min-height*/

    min-height:100%; /* real browsers */

div#header {
    background:#ddd url("../csslayout.gif") 98% 10px no-repeat;
    border-bottom:6px double gray;
    div#header p {

div#content {
    padding:1em 1em 5em; /* bottom padding for footer */
    div#content p {
        padding:0 1em;

div#footer {
    bottom:0; /* stick to bottom */
    border-top:6px double gray;
div#footer p {

Works fine for me.

Difference between EXISTS and IN in SQL?


  • Works on List result set
  • Doesn’t work on subqueries resulting in Virtual tables with multiple columns
  • Compares every value in the result list
  • Performance is comparatively SLOW for larger result set of subquery


  • Works on Virtual tables
  • Is used with co-related queries
  • Exits comparison when match is found
  • Performance is comparatively FAST for larger result set of subquery

Is there a performance difference between i++ and ++i in C?

Please don't let the question of "which one is faster" be the deciding factor of which to use. Chances are you're never going to care that much, and besides, programmer reading time is far more expensive than machine time.

Use whichever makes most sense to the human reading the code.

How do I fix "for loop initial declaration used outside C99 mode" GCC error?

There is a compiler switch which enables C99 mode, which amongst other things allows declaration of a variable inside the for loop. To turn it on use the compiler switch -std=c99

Or as @OysterD says, declare the variable outside the loop.

C: What is the difference between ++i and i++?

Here is the example to understand the difference

int i=10;
printf("%d %d",i++,++i);

output: 10 12/11 11 (depending on the order of evaluation of arguments to the printf function, which varies across compilers and architectures)

Explanation: i++->i is printed, and then increments. (Prints 10, but i will become 11) ++i->i value increments and prints the value. (Prints 12, and the value of i also 12)

Execute script after specific delay using JavaScript

You can also use window.setInterval() to run some code repeatedly at a regular interval.

Escaping HTML strings with jQuery

I wrote a tiny little function which does this. It only escapes ", &, < and > (but usually that's all you need anyway). It is slightly more elegant then the earlier proposed solutions in that it only uses one .replace() to do all the conversion. (EDIT 2: Reduced code complexity making the function even smaller and neater, if you're curious about the original code see end of this answer.)

function escapeHtml(text) {
    'use strict';
    return text.replace(/[\"&<>]/g, function (a) {
        return { '"': '&quot;', '&': '&amp;', '<': '&lt;', '>': '&gt;' }[a];

This is plain Javascript, no jQuery used.

Escaping / and ' too

Edit in response to mklement's comment.

The above function can easily be expanded to include any character. To specify more characters to escape, simply insert them both in the character class in the regular expression (i.e. inside the /[...]/g) and as an entry in the chr object. (EDIT 2: Shortened this function too, in the same way.)

function escapeHtml(text) {
    'use strict';
    return text.replace(/[\"&'\/<>]/g, function (a) {
        return {
            '"': '&quot;', '&': '&amp;', "'": '&#39;',
            '/': '&#47;',  '<': '&lt;',  '>': '&gt;'

Note the above use of &#39; for apostrophe (the symbolic entity &apos; might have been used instead – it is defined in XML, but was originally not included in the HTML spec and might therefore not be supported by all browsers. See: Wikipedia article on HTML character encodings). I also recall reading somewhere that using decimal entities is more widely supported than using hexadecimal, but I can't seem to find the source for that now though. (And there cannot be many browsers out there which does not support the hexadecimal entities.)

Note: Adding / and ' to the list of escaped characters isn't all that useful, since they do not have any special meaning in HTML and do not need to be escaped.

Original escapeHtml Function

EDIT 2: The original function used a variable (chr) to store the object needed for the .replace() callback. This variable also needed an extra anonymous function to scope it, making the function (needlessly) a little bit bigger and more complex.

var escapeHtml = (function () {
    'use strict';
    var chr = { '"': '&quot;', '&': '&amp;', '<': '&lt;', '>': '&gt;' };
    return function (text) {
        return text.replace(/[\"&<>]/g, function (a) { return chr[a]; });

I haven't tested which of the two versions are faster. If you do, feel free to add info and links about it here.

JavaScript editor within Eclipse

Eclipse HTML Editor Plugin

I too have struggled with this totally obvious question. It seemed crazy that this wasn't an extremely easy-to-find feature with all the web development happening in Eclipse these days.

I was very turned off by Aptana because of how bloated it is, and the fact that it starts up a local web server (by default on port 8000) everytime you start Eclipse and you can't disable this functionality. Adobe's port of JSEclipse is now a 400Mb plugin, which is equally insane.

However, I just found a super-lightweight JavaScript editor called Eclipse HTML Editor Plugin, made by Amateras, which was exactly what I was looking for.

Abstraction VS Information Hiding VS Encapsulation

See Joel's post on the Law of Leaky Abstractions


Basically, abstracting gives you the freedom of thinking of higher level concepts. A non-programming analogy is that most of us do not know where our food comes from, or how it is produced, but the fact that we (usually) don't have to worry about it frees us up to do other things, like programming.

As for information hiding, I agree with jamting.

Initialize class fields in constructor or at declaration?

The design of C# suggests that inline initialization is preferred, or it wouldn't be in the language. Any time you can avoid a cross-reference between different places in the code, you're generally better off.

There is also the matter of consistency with static field initialization, which needs to be inline for best performance. The Framework Design Guidelines for Constructor Design say this:

? CONSIDER initializing static fields inline rather than explicitly using static constructors, because the runtime is able to optimize the performance of types that don’t have an explicitly defined static constructor.

"Consider" in this context means to do so unless there's a good reason not to. In the case of static initializer fields, a good reason would be if initialization is too complex to be coded inline.

SQL Server: Examples of PIVOTing String data

Remember that the MAX aggregate function will work on text as well as numbers. This query will only require the table to be scanned once.

SELECT Action,
       MAX( CASE data WHEN 'View' THEN data ELSE '' END ) ViewCol, 
       MAX( CASE data WHEN 'Edit' THEN data ELSE '' END ) EditCol
 GROUP BY Action

C++ IDE for Linux?

SlickEdit. I have used and loved SlickEdit since 2005, both on Windows and on Linux. I also have experience working in Visual Studio (5, 6, 2003, 2005) and just with Emacs and command line. I use SlickEdit with external makefiles, some of my teammates use SlickEdit, others use Emacs/vi. I do not use the integrated debugger, integrated version control, integrated build system: I generally find too much integration to be real pain. SlickEdit is robust (very few bugs), fast and intuitive. It is like a German car, a driver's car.

The newest versions of SlickEdit seem to offer many features that do not interest me, I am a little worried that the product will become bloated and diluted in the future. For now (I use V13.0) it is great.

Algorithm to compare two images

It is indeed much less simple than it seems :-) Nick's suggestion is a good one.

To get started, keep in mind that any worthwhile comparison method will essentially work by converting the images into a different form -- a form which makes it easier to pick similar features out. Usually, this stuff doesn't make for very light reading ...

One of the simplest examples I can think of is simply using the color space of each image. If two images have highly similar color distributions, then you can be reasonably sure that they show the same thing. At least, you can have enough certainty to flag it, or do more testing. Comparing images in color space will also resist things such as rotation, scaling, and some cropping. It won't, of course, resist heavy modification of the image or heavy recoloring (and even a simple hue shift will be somewhat tricky).

Another example involves something called the Hough Transform. This transform essentially decomposes an image into a set of lines. You can then take some of the 'strongest' lines in each image and see if they line up. You can do some extra work to try and compensate for rotation and scaling too -- and in this case, since comparing a few lines is MUCH less computational work than doing the same to entire images -- it won't be so bad.

What does 'IISReset' do?

IISReset restarts the entire webserver (including all associated sites). If you're just looking to reset a single ASP.NET website, you should just recycle that AppDomain.

The most common way to reset an ASP.NET website is to edit the web.config file, but you can also create an admin page with the following:

public partial class Recycle : System.Web.UI.Page
    protected void Page_Load(object sender, EventArgs e)

Here's a blog post I wrote with more info: Avoid IISRESET in ASP.NET Applications

How Best to Compare Two Collections in Java and Act on Them?

For a set that small is generally not worth it to convert from an Array to a HashMap/set. In fact, you're probably best off keeping them in an array and then sorting them by key and iterating over both lists simultaneously to do the comparison.