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Remove columns from DataTable in C#

Aside from limiting the columns selected to reduce bandwidth and memory:

DataTable t;
t.Columns.Remove("columnName");
t.Columns.RemoveAt(columnIndex);

What datatype should be used for storing phone numbers in SQL Server 2005?

SQL Server 2005 is pretty well optimized for substring queries for text in indexed varchar fields. For 2005 they introduced new statistics to the string summary for index fields. This helps significantly with full text searching.

Is there a PowerShell "string does not contain" cmdlet or syntax?

To exclude the lines that contain any of the strings in $arrayOfStringsNotInterestedIn, you should use:

(Get-Content $FileName) -notmatch [String]::Join('|',$arrayofStringsNotInterestedIn)

The code proposed by Chris only works if $arrayofStringsNotInterestedIn contains the full lines you want to exclude.

Any tools to generate an XSD schema from an XML instance document?

There also is XML schema learner which is available on Github.

It can take multiple xml files and extract a common XSD from all of those files.

Bash or KornShell (ksh)?

Bash is the benchmark, but that's mostly because you can be reasonably sure it's installed on every *nix out there. If you're planning to distribute the scripts, use Bash.

I can not really address the actual programming differences between the shells, unfortunately.

How do I check CPU and Memory Usage in Java?

If you are using Tomcat, check out Psi Probe, which lets you monitor internal and external memory consumption as well as a host of other areas.

How do you force a CIFS connection to unmount

On RHEL 6 this worked for me also:

umount -f -a -t cifs -l FOLDER_NAME

How to convert DateTime to VarChar

Try the following:

CONVERT(VARCHAR(10),GetDate(),102)

Then you would need to replace the "." with "-".

Here is a site that helps http://www.mssqltips.com/tip.asp?tip=1145

How to do INSERT into a table records extracted from another table

Well I think the best way would be (will be?) to define 2 recordsets and use them as an intermediate between the 2 tables.

  1. Open both recordsets
  2. Extract the data from the first table (SELECT blablabla)
  3. Update 2nd recordset with data available in the first recordset (either by adding new records or updating existing records
  4. Close both recordsets

This method is particularly interesting if you plan to update tables from different databases (ie each recordset can have its own connection ...)

How to convert numbers between hexadecimal and decimal

My version is I think a little more understandable because my C# knowledge is not so high. I'm using this algorithm: http://easyguyevo.hubpages.com/hub/Convert-Hex-to-Decimal (The Example 2)

using System;
using System.Collections.Generic;

static class Tool
{
    public static string DecToHex(int x)
    {
        string result = "";

        while (x != 0)
        {
            if ((x % 16) < 10)
                result = x % 16 + result;
            else
            {
                string temp = "";

                switch (x % 16)
                {
                    case 10: temp = "A"; break;
                    case 11: temp = "B"; break;
                    case 12: temp = "C"; break;
                    case 13: temp = "D"; break;
                    case 14: temp = "E"; break;
                    case 15: temp = "F"; break;
                }

                result = temp + result;
            }

            x /= 16;
        }

        return result;
    }

    public static int HexToDec(string x)
    {
        int result = 0;
        int count = x.Length - 1;
        for (int i = 0; i < x.Length; i++)
        {
            int temp = 0;
            switch (x[i])
            {
                case 'A': temp = 10; break;
                case 'B': temp = 11; break;
                case 'C': temp = 12; break;
                case 'D': temp = 13; break;
                case 'E': temp = 14; break;
                case 'F': temp = 15; break;
                default: temp = -48 + (int)x[i]; break; // -48 because of ASCII
            }

            result += temp * (int)(Math.Pow(16, count));
            count--;
        }

        return result;
    }
}

class Program
{
    static void Main(string[] args)
    {
        Console.Write("Enter Decimal value: ");
        int decNum = int.Parse(Console.ReadLine());

        Console.WriteLine("Dec {0} is hex {1}", decNum, Tool.DecToHex(decNum));

        Console.Write("\nEnter Hexadecimal value: ");
        string hexNum = Console.ReadLine().ToUpper();

        Console.WriteLine("Hex {0} is dec {1}", hexNum, Tool.HexToDec(hexNum));

        Console.ReadKey();
    }
}

What is the difference between explicit and implicit cursors in Oracle?

In answer to the first question. Straight from the Oracle documentation

A cursor is a pointer to a private SQL area that stores information about processing a specific SELECT or DML statement.

Dropdownlist width in IE

Based on the solution posted by Sai, this is how to do it with jQuery.

$(document).ready(function() {
    if ($.browser.msie) $('select.wide')
        .bind('onmousedown', function() { $(this).css({position:'absolute',width:'auto'}); })
        .bind('blur', function() { $(this).css({position:'static',width:''}); });
});

String vs. StringBuilder

I have seen significant performance gains from using the EnsureCapacity(int capacity) method call on an instance of StringBuilder before using it for any string storage. I usually call that on the line of code after instantiation. It has the same effect as if you instantiate the StringBuilder like this:

var sb = new StringBuilder(int capacity);

This call allocates needed memory ahead of time, which causes fewer memory allocations during multiple Append() operations. You have to make an educated guess on how much memory you will need, but for most applications this should not be too difficult. I usually err on the side of a little too much memory (we are talking 1k or so).

Iterating through all the cells in Excel VBA or VSTO 2005

There are several methods to accomplish this, each of which has advantages and disadvantages; First and foremost, you're going to need to have an instance of a Worksheet object, Application.ActiveSheet works if you just want the one the user is looking at.

The Worksheet object has three properties that can be used to access cell data (Cells, Rows, Columns) and a method that can be used to obtain a block of cell data, (get_Range).

Ranges can be resized and such, but you may need to use the properties mentioned above to find out where the boundaries of your data are. The advantage to a Range becomes apparent when you are working with large amounts of data because VSTO add-ins are hosted outside the boundaries of the Excel application itself, so all calls to Excel have to be passed through a layer with overhead; obtaining a Range allows you to get/set all of the data you want in one call which can have huge performance benefits, but it requires you to use explicit details rather than iterating through each entry.

This MSDN forum post shows a VB.Net developer asking a question about getting the results of a Range as an array

What is the dual table in Oracle?

DUAL we mainly used for getting the next number from the sequences.

Syntax : SELECT 'sequence_name'.NEXTVAL FROM DUAL

This will return the one row one column value(NEXTVAL column name).

How can I start an interactive console for Perl?

There isn't an interactive console for Perl built in like Python does. You can however use the Perl Debugger to do debugging related things. You turn it on with the -d option, but you might want to check out 'man perldebug' to learn about it.

After a bit of googling, there is a separate project that implements a Perl console which you can find at http://www.sukria.net/perlconsole.html.

Hope this helps!

How to terminate a Python script

My two cents.

Python 3.8.1, Windows 10, 64-bit.

sys.exit() does not work directly for me.

I have several nexted loops.

First I declare a boolean variable, which I call immediateExit.

So, in the beginning of the program code I write:

immediateExit = False

Then, starting from the most inner (nested) loop exception, I write:

            immediateExit = True
            sys.exit('CSV file corrupted 0.')

Then I go into the immediate continuation of the outer loop, and before anything else being executed by the code, I write:

    if immediateExit:
        sys.exit('CSV file corrupted 1.')

Depending on the complexity, sometimes the above statement needs to be repeated also in except sections, etc.

    if immediateExit:
        sys.exit('CSV file corrupted 1.5.')

The custom message is for my personal debugging, as well, as the numbers are for the same purpose - to see where the script really exits.

'CSV file corrupted 1.5.'

In my particular case I am processing a CSV file, which I do not want the software to touch, if the software detects it is corrupted. Therefore for me it is very important to exit the whole Python script immediately after detecting the possible corruption.

And following the gradual sys.exit-ing from all the loops I manage to do it.

Full code: (some changes were needed because it is proprietory code for internal tasks):

immediateExit = False
start_date = '1994.01.01'
end_date = '1994.01.04'
resumedDate = end_date


end_date_in_working_days = False
while not end_date_in_working_days:
    try:
        end_day_position = working_days.index(end_date)

        end_date_in_working_days = True
    except ValueError: # try statement from end_date in workdays check
        print(current_date_and_time())
        end_date = input('>> {} is not in the list of working days. Change the date (YYYY.MM.DD): '.format(end_date))
        print('New end date: ', end_date, '\n')
        continue


    csv_filename = 'test.csv'
    csv_headers = 'date,rate,brand\n' # not real headers, this is just for example
    try:
        with open(csv_filename, 'r') as file:
            print('***\nOld file {} found. Resuming the file by re-processing the last date lines.\nThey shall be deleted and re-processed.\n***\n'.format(csv_filename))
            last_line = file.readlines()[-1]
            start_date = last_line.split(',')[0] # assigning the start date to be the last like date.
            resumedDate = start_date

            if last_line == csv_headers:
                pass
            elif start_date not in working_days:
                print('***\n\n{} file might be corrupted. Erase or edit the file to continue.\n***'.format(csv_filename))
                immediateExit = True
                sys.exit('CSV file corrupted 0.')
            else:
                start_date = last_line.split(',')[0] # assigning the start date to be the last like date.
                print('\nLast date:', start_date)
                file.seek(0) # setting the cursor at the beginnning of the file
                lines = file.readlines() # reading the file contents into a list
                count = 0 # nr. of lines with last date
                for line in lines: #cycling through the lines of the file
                    if line.split(',')[0] == start_date: # cycle for counting the lines with last date in it.
                        count = count + 1
        if immediateExit:
            sys.exit('CSV file corrupted 1.')
        for iter in range(count): # removing the lines with last date
            lines.pop()
        print('\n{} lines removed from date: {} in {} file'.format(count, start_date, csv_filename))



        if immediateExit:
            sys.exit('CSV file corrupted 1.2.')
        with open(csv_filename, 'w') as file:
            print('\nFile', csv_filename, 'open for writing')
            file.writelines(lines)

            print('\nRemoving', count, 'lines from', csv_filename)

        fileExists = True

    except:
        if immediateExit:
            sys.exit('CSV file corrupted 1.5.')
        with open(csv_filename, 'w') as file:
            file.write(csv_headers)
            fileExists = False
    if immediateExit:
        sys.exit('CSV file corrupted 2.')

How to duplicate a whole line in Vim?

If you want another way:

"ayy: This will store the line in buffer a.

"ap: This will put the contents of buffer a at the cursor.

There are many variations on this.

"a5yy: This will store the 5 lines in buffer a.

See "Vim help files for more fun.

How do I sort a list of dictionaries by a value of the dictionary?

I have been a big fan of a filter with lambda. However, it is not best option if you consider time complexity.

First option

sorted_list = sorted(list_to_sort, key= lambda x: x['name'])
# Returns list of values

Second option

list_to_sort.sort(key=operator.itemgetter('name'))
# Edits the list, and does not return a new list

Fast comparison of execution times

# First option
python3.6 -m timeit -s "list_to_sort = [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}, {'name':'Faaa', 'age':57}, {'name':'Errr', 'age':20}]" -s "sorted_l=[]" "sorted_l = sorted(list_to_sort, key=lambda e: e['name'])"

1000000 loops, best of 3: 0.736 µsec per loop

# Second option
python3.6 -m timeit -s "list_to_sort = [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}, {'name':'Faaa', 'age':57}, {'name':'Errr', 'age':20}]" -s "sorted_l=[]" -s "import operator" "list_to_sort.sort(key=operator.itemgetter('name'))"

1000000 loops, best of 3: 0.438 µsec per loop

How to do relative imports in Python?

I found it's more easy to set "PYTHONPATH" enviroment variable to the top folder:

bash$ export PYTHONPATH=/PATH/TO/APP

then:

import sub1.func1
#...more import

of course, PYTHONPATH is "global", but it didn't raise trouble for me yet.

How do I capitalize first letter of first name and last name in C#?

CultureInfo.CurrentCulture.TextInfo.ToTitleCase ("my name");

returns ~ My Name

But the problem still exists with names like McFly as stated earlier.

How do you detect Credit card type based on number?

In javascript:

function detectCardType(number) {
    var re = {
        electron: /^(4026|417500|4405|4508|4844|4913|4917)\d+$/,
        maestro: /^(5018|5020|5038|5612|5893|6304|6759|6761|6762|6763|0604|6390)\d+$/,
        dankort: /^(5019)\d+$/,
        interpayment: /^(636)\d+$/,
        unionpay: /^(62|88)\d+$/,
        visa: /^4[0-9]{12}(?:[0-9]{3})?$/,
        mastercard: /^5[1-5][0-9]{14}$/,
        amex: /^3[47][0-9]{13}$/,
        diners: /^3(?:0[0-5]|[68][0-9])[0-9]{11}$/,
        discover: /^6(?:011|5[0-9]{2})[0-9]{12}$/,
        jcb: /^(?:2131|1800|35\d{3})\d{11}$/
    }

    for(var key in re) {
        if(re[key].test(number)) {
            return key
        }
    }
}

Unit test:

describe('CreditCard', function() {
    describe('#detectCardType', function() {

        var cards = {
            '8800000000000000': 'UNIONPAY',

            '4026000000000000': 'ELECTRON',
            '4175000000000000': 'ELECTRON',
            '4405000000000000': 'ELECTRON',
            '4508000000000000': 'ELECTRON',
            '4844000000000000': 'ELECTRON',
            '4913000000000000': 'ELECTRON',
            '4917000000000000': 'ELECTRON',

            '5019000000000000': 'DANKORT',

            '5018000000000000': 'MAESTRO',
            '5020000000000000': 'MAESTRO',
            '5038000000000000': 'MAESTRO',
            '5612000000000000': 'MAESTRO',
            '5893000000000000': 'MAESTRO',
            '6304000000000000': 'MAESTRO',
            '6759000000000000': 'MAESTRO',
            '6761000000000000': 'MAESTRO',
            '6762000000000000': 'MAESTRO',
            '6763000000000000': 'MAESTRO',
            '0604000000000000': 'MAESTRO',
            '6390000000000000': 'MAESTRO',

            '3528000000000000': 'JCB',
            '3589000000000000': 'JCB',
            '3529000000000000': 'JCB',

            '6360000000000000': 'INTERPAYMENT',

            '4916338506082832': 'VISA',
            '4556015886206505': 'VISA',
            '4539048040151731': 'VISA',
            '4024007198964305': 'VISA',
            '4716175187624512': 'VISA',

            '5280934283171080': 'MASTERCARD',
            '5456060454627409': 'MASTERCARD',
            '5331113404316994': 'MASTERCARD',
            '5259474113320034': 'MASTERCARD',
            '5442179619690834': 'MASTERCARD',

            '6011894492395579': 'DISCOVER',
            '6011388644154687': 'DISCOVER',
            '6011880085013612': 'DISCOVER',
            '6011652795433988': 'DISCOVER',
            '6011375973328347': 'DISCOVER',

            '345936346788903': 'AMEX',
            '377669501013152': 'AMEX',
            '373083634595479': 'AMEX',
            '370710819865268': 'AMEX',
            '371095063560404': 'AMEX'
        };

        Object.keys(cards).forEach(function(number) {
            it('should detect card ' + number + ' as ' + cards[number], function() {
                Basket.detectCardType(number).should.equal(cards[number]);
            });
        });
    });
});

Accessing Websites through a Different Port?

You can run the web server on any port. 80 is just convention as are 8080 (web server on unprivileged port) and 443 (web server + ssl). However if you're looking to see some web site by pointing your browser to a different port you're probably out of luck. Unless the web server is being run on that port explicitly you'll just get an error message.

How often should Oracle database statistics be run?

With 10g and higher version of oracle, up to date statistics on tables and indexes are needed by the optimizer to make "good" execution plan decision. How often you collect statistics is a tricky call. It depends on your application, schema, data rate and business practice. Some third party apps which are written to be backward compatible with older version of oracle do not perform well with the new optimizer. Those application require that tables have no stats so that the db resorts back to rule base execution plan. But on the average oracle recommends that stats be collected on tables with stale statistics. You can set tables to be monitor and check their state and have them analyze if/when stale. Often that is enough, sometime it is not. It really depend on your database. For my database we have a set of OLTP tables that need nightly stats collection to maintain performance. Other tables are analyze once a week. On our large dw database, we analyze as needed as the tables are too large for regular analysis without affecting overall db load and performance. So the correct answer is, it depends on the application, data change and business needs.

How do I migrate an SVN repository with history to a new Git repository?

Cleanly Migrate Your Subversion Repository To a Git Repository. First you have to create a file that maps your Subversion commit author names to Git commiters, say ~/authors.txt:

jmaddox = Jon Maddox <[email protected]>
bigpappa = Brian Biggs <[email protected]>

Then you can download the Subversion data into a Git repository:

mkdir repo && cd repo
git svn init http://subversion/repo --no-metadata
git config svn.authorsfile ~/authors.txt
git svn fetch

If you’re on a Mac, you can get git-svn from MacPorts by installing git-core +svn.

If your subversion repository is on the same machine as your desired git repository, then you can use this syntax for the init step, otherwise all the same:

git svn init file:///home/user/repoName --no-metadata

Create Generic method constraining T to an Enum

Just for completeness, the following is a Java solution. I am certain the same could be done in C# as well. It avoids having to specify the type anywhere in code - instead, you specify it in the strings you are trying to parse.

The problem is that there isn't any way to know which enumeration the String might match - so the answer is to solve that problem.

Instead of accepting just the string value, accept a String that has both the enumeration and the value in the form "enumeration.value". Working code is below - requires Java 1.8 or later. This would also make the XML more precise as in you would see something like color="Color.red" instead of just color="red".

You would call the acceptEnumeratedValue() method with a string containing the enum name dot value name.

The method returns the formal enumerated value.

import java.util.HashMap;
import java.util.Map;
import java.util.function.Function;


public class EnumFromString {

    enum NumberEnum {One, Two, Three};
    enum LetterEnum {A, B, C};


    Map<String, Function<String, ? extends Enum>> enumsByName = new HashMap<>();

    public static void main(String[] args) {
        EnumFromString efs = new EnumFromString();

        System.out.print("\nFirst string is NumberEnum.Two - enum is " + efs.acceptEnumeratedValue("NumberEnum.Two").name());
        System.out.print("\nSecond string is LetterEnum.B - enum is " + efs.acceptEnumeratedValue("LetterEnum.B").name());

    }

    public EnumFromString() {
        enumsByName.put("NumberEnum", s -> {return NumberEnum.valueOf(s);});
        enumsByName.put("LetterEnum", s -> {return LetterEnum.valueOf(s);});
    }

    public Enum acceptEnumeratedValue(String enumDotValue) {

        int pos = enumDotValue.indexOf(".");

        String enumName = enumDotValue.substring(0, pos);
        String value = enumDotValue.substring(pos + 1);

        Enum enumeratedValue = enumsByName.get(enumName).apply(value);

        return enumeratedValue;
    }


}

Is there a C++ gdb GUI for Linux?

I've tried a couple of different guis for gdb and have found DDD to be the better of them. And while I can't comment on other, non-gdb offerings for linux I've used a number of other debuggers on other platforms.

gdb does the majority of the things that you have in your wish list. DDD puts a nicer front on them. For example thread switching is made simpler. Setting breakpoints is as simple as you would expect.

You also get a cli window in case there is something obscure that you want to do.

The one feature of DDD that stands out above any other debugger that I've used is the data "graphing". This allows you to display and arrange structures, objects and memory as draggable boxes. Double clicking a pointer will open up the dereferenced data with visual links back to the parent.

How do I programmatically set the value of a select box element using JavaScript?

Why not add a variable for the element's Id and make it a reusable function?

function SelectElement(selectElementId, valueToSelect)
{    
    var element = document.getElementById(selectElementId);
    element.value = valueToSelect;
}

Deep cloning objects

To clone your class object you can use the Object.MemberwiseClone method,

just add this function to your class :

public class yourClass
{
    // ...
    // ...

    public yourClass DeepCopy()
    {
        yourClass othercopy = (yourClass)this.MemberwiseClone();
        return othercopy;
    }
}

then to perform a deep independant copy, just call the DeepCopy method :

yourClass newLine = oldLine.DeepCopy();

hope this helps.

How do you get a string from a MemoryStream?

Previous solutions wouldn't work in cases where encoding is involved. Here is - kind of a "real life" - example how to do this properly...

using(var stream = new System.IO.MemoryStream())
{
  var serializer = new DataContractJsonSerializer(typeof(IEnumerable<ExportData>),  new[]{typeof(ExportData)}, Int32.MaxValue, true, null, false);               
  serializer.WriteObject(stream, model);  


  var jsonString = Encoding.Default.GetString((stream.ToArray()));
}

Why doesn't Java offer operator overloading?

James Gosling likened designing Java to the following:

"There's this principle about moving, when you move from one apartment to another apartment. An interesting experiment is to pack up your apartment and put everything in boxes, then move into the next apartment and not unpack anything until you need it. So you're making your first meal, and you're pulling something out of a box. Then after a month or so you've used that to pretty much figure out what things in your life you actually need, and then you take the rest of the stuff -- forget how much you like it or how cool it is -- and you just throw it away. It's amazing how that simplifies your life, and you can use that principle in all kinds of design issues: not do things just because they're cool or just because they're interesting."

You can read the context of the quote here

Basically operator overloading is great for a class that models some kind of point, currency or complex number. But after that you start running out of examples fast.

Another factor was the abuse of the feature in C++ by developers overloading operators like '&&', '||', the cast operators and of course 'new'. The complexity resulting from combining this with pass by value and exceptions is well covered in the Exceptional C++ book.

How do you run CMD.exe under the Local System Account?

if you can write a batch file that does not need to be interactive, try running that batch file as a service, to do what needs to be done.

How to access the last value in a vector?

To answer this not from an aesthetical but performance-oriented point of view, I've put all of the above suggestions through a benchmark. To be precise, I've considered the suggestions

  • x[length(x)]
  • mylast(x), where mylast is a C++ function implemented through Rcpp,
  • tail(x, n=1)
  • dplyr::last(x)
  • x[end(x)[1]]]
  • rev(x)[1]

and applied them to random vectors of various sizes (10^3, 10^4, 10^5, 10^6, and 10^7). Before we look at the numbers, I think it should be clear that anything that becomes noticeably slower with greater input size (i.e., anything that is not O(1)) is not an option. Here's the code that I used:

Rcpp::cppFunction('double mylast(NumericVector x) { int n = x.size(); return x[n-1]; }')
options(width=100)
for (n in c(1e3,1e4,1e5,1e6,1e7)) {
  x <- runif(n);
  print(microbenchmark::microbenchmark(x[length(x)],
                                       mylast(x),
                                       tail(x, n=1),
                                       dplyr::last(x),
                                       x[end(x)[1]],
                                       rev(x)[1]))}

It gives me

Unit: nanoseconds
           expr   min      lq     mean  median      uq   max neval
   x[length(x)]   171   291.5   388.91   337.5   390.0  3233   100
      mylast(x)  1291  1832.0  2329.11  2063.0  2276.0 19053   100
 tail(x, n = 1)  7718  9589.5 11236.27 10683.0 12149.0 32711   100
 dplyr::last(x) 16341 19049.5 22080.23 21673.0 23485.5 70047   100
   x[end(x)[1]]  7688 10434.0 13288.05 11889.5 13166.5 78536   100
      rev(x)[1]  7829  8951.5 10995.59  9883.0 10890.0 45763   100
Unit: nanoseconds
           expr   min      lq     mean  median      uq    max neval
   x[length(x)]   204   323.0   475.76   386.5   459.5   6029   100
      mylast(x)  1469  2102.5  2708.50  2462.0  2995.0   9723   100
 tail(x, n = 1)  7671  9504.5 12470.82 10986.5 12748.0  62320   100
 dplyr::last(x) 15703 19933.5 26352.66 22469.5 25356.5 126314   100
   x[end(x)[1]] 13766 18800.5 27137.17 21677.5 26207.5  95982   100
      rev(x)[1] 52785 58624.0 78640.93 60213.0 72778.0 851113   100
Unit: nanoseconds
           expr     min        lq       mean    median        uq     max neval
   x[length(x)]     214     346.0     583.40     529.5     720.0    1512   100
      mylast(x)    1393    2126.0    4872.60    4905.5    7338.0    9806   100
 tail(x, n = 1)    8343   10384.0   19558.05   18121.0   25417.0   69608   100
 dplyr::last(x)   16065   22960.0   36671.13   37212.0   48071.5   75946   100
   x[end(x)[1]]  360176  404965.5  432528.84  424798.0  450996.0  710501   100
      rev(x)[1] 1060547 1140149.0 1189297.38 1180997.5 1225849.0 1383479   100
Unit: nanoseconds
           expr     min        lq        mean    median         uq      max neval
   x[length(x)]     327     584.0     1150.75     996.5     1652.5     3974   100
      mylast(x)    2060    3128.5     7541.51    8899.0     9958.0    16175   100
 tail(x, n = 1)   10484   16936.0    30250.11   34030.0    39355.0    52689   100
 dplyr::last(x)   19133   47444.5    55280.09   61205.5    66312.5   105851   100
   x[end(x)[1]] 1110956 2298408.0  3670360.45 2334753.0  4475915.0 19235341   100
      rev(x)[1] 6536063 7969103.0 11004418.46 9973664.5 12340089.5 28447454   100
Unit: nanoseconds
           expr      min         lq         mean      median          uq       max neval
   x[length(x)]      327      722.0      1644.16      1133.5      2055.5     13724   100
      mylast(x)     1962     3727.5      9578.21      9951.5     12887.5     41773   100
 tail(x, n = 1)     9829    21038.0     36623.67     43710.0     48883.0     66289   100
 dplyr::last(x)    21832    35269.0     60523.40     63726.0     75539.5    200064   100
   x[end(x)[1]] 21008128 23004594.5  37356132.43  30006737.0  47839917.0 105430564   100
      rev(x)[1] 74317382 92985054.0 108618154.55 102328667.5 112443834.0 187925942   100

This immediately rules out anything involving rev or end since they're clearly not O(1) (and the resulting expressions are evaluated in a non-lazy fashion). tail and dplyr::last are not far from being O(1) but they're also considerably slower than mylast(x) and x[length(x)]. Since mylast(x) is slower than x[length(x)] and provides no benefits (rather, it's custom and does not handle an empty vector gracefully), I think the answer is clear: Please use x[length(x)].

When to throw an exception?

If it's code running inside a loop that will likely cause an exception over and over again, then throwing exceptions is not a good thing, because they are pretty slow for large N. But there is nothing wrong with throwing custom exceptions if the performance is not an issue. Just make sure that you have a base exception that they all inherite, called BaseException or something like that. BaseException inherits System.Exception, but all of your exceptions inherit BaseException. You can even have a tree of Exception types to group similar types, but this may or may not be overkill.

So, the short answer is that if it doesn't cause a significant performance penalty (which it should not unless you are throwing a lot of exceptions), then go ahead.

How to automatically generate a stacktrace when my program crashes

For Linux and I believe Mac OS X, if you're using gcc, or any compiler that uses glibc, you can use the backtrace() functions in execinfo.h to print a stacktrace and exit gracefully when you get a segmentation fault. Documentation can be found in the libc manual.

Here's an example program that installs a SIGSEGV handler and prints a stacktrace to stderr when it segfaults. The baz() function here causes the segfault that triggers the handler:

#include <stdio.h>
#include <execinfo.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>


void handler(int sig) {
  void *array[10];
  size_t size;

  // get void*'s for all entries on the stack
  size = backtrace(array, 10);

  // print out all the frames to stderr
  fprintf(stderr, "Error: signal %d:\n", sig);
  backtrace_symbols_fd(array, size, STDERR_FILENO);
  exit(1);
}

void baz() {
 int *foo = (int*)-1; // make a bad pointer
  printf("%d\n", *foo);       // causes segfault
}

void bar() { baz(); }
void foo() { bar(); }


int main(int argc, char **argv) {
  signal(SIGSEGV, handler);   // install our handler
  foo(); // this will call foo, bar, and baz.  baz segfaults.
}

Compiling with -g -rdynamic gets you symbol info in your output, which glibc can use to make a nice stacktrace:

$ gcc -g -rdynamic ./test.c -o test

Executing this gets you this output:

$ ./test
Error: signal 11:
./test(handler+0x19)[0x400911]
/lib64/tls/libc.so.6[0x3a9b92e380]
./test(baz+0x14)[0x400962]
./test(bar+0xe)[0x400983]
./test(foo+0xe)[0x400993]
./test(main+0x28)[0x4009bd]
/lib64/tls/libc.so.6(__libc_start_main+0xdb)[0x3a9b91c4bb]
./test[0x40086a]

This shows the load module, offset, and function that each frame in the stack came from. Here you can see the signal handler on top of the stack, and the libc functions before main in addition to main, foo, bar, and baz.

How to get progress from XMLHttpRequest

For the total uploaded there doesn't seem to be a way to handle that, but there's something similar to what you want for download. Once readyState is 3, you can periodically query responseText to get all the content downloaded so far as a String (this doesn't work in IE), up until all of it is available at which point it will transition to readyState 4. The total bytes downloaded at any given time will be equal to the total bytes in the string stored in responseText.

For a all or nothing approach to the upload question, since you have to pass a string for upload (and it's possible to determine the total bytes of that) the total bytes sent for readyState 0 and 1 will be 0, and the total for readyState 2 will be the total bytes in the string you passed in. The total bytes both sent and received in readyState 3 and 4 will be the sum of the bytes in the original string plus the total bytes in responseText.

General guidelines to avoid memory leaks in C++

If you can, use boost shared_ptr and standard C++ auto_ptr. Those convey ownership semantics.

When you return an auto_ptr, you are telling the caller that you are giving them ownership of the memory.

When you return a shared_ptr, you are telling the caller that you have a reference to it and they take part of the ownership, but it isn't solely their responsibility.

These semantics also apply to parameters. If the caller passes you an auto_ptr, they are giving you ownership.

SOAP or REST for Web Services?

My general rule is that if you want a browser web client to directly connect to a service then you should probably use REST. If you want to pass structured data between back-end services then use SOAP.

SOAP can be a real pain to set up sometimes and is often overkill for simple web client and server data exchanges. Unfortunately, most simple programming examples I've seen (and learned from) somewhat reenforce this perception.

That said, SOAP really shines when you start combining multiple SOAP services together as part of a larger process driven by a data workflow (think enterprise software). This is something that many of the SOAP programming examples fail to convey because a simple SOAP operation to do something, like fetch the price of a stock, is generally overcomplicated for what it does by itself unless it is presented in the context of providing a machine readable API detailing specific functions with set data formats for inputs and outputs that is, in turn, scripted by a larger process.

This is sad, in a way, as it really gives SOAP a bad reputation because it is difficult to show the advantages of SOAP without presenting it in the full context of how the final product is used.

Change the color of a bullet in a html list?

This was impossible in 2008, but it's becoming possible soon (hopefully)!

According to The W3C CSS3 specification, you can have full control over any number, glyph, or other symbol generated before a list item with the ::marker pseudo-element. To apply this to the most voted answer's solution:

<ul>
  <li>item #1</li>
  <li>item #2</li>
  <li>item #3</li>
</ul>

li::marker {
  color: red; /* bullet color */
}
li {
  color: black /* text color */
}

JSFiddle Example

Note, though, that as of July 2016, this solution is only a part of the W3C Working Draft and does not work in any major browsers, yet.

If you want this feature, do these:

How can I open Java .class files in a human-readable way?

You need to use a decompiler. Others have suggested JAD, there are other options, JAD is the best.

I'll echo the comments that you may lose a bit compared to the original source code. It is going to look especially funny if the code used generics, due to erasure.

How can I delete a service in Windows?

If you have Windows Vista or above please run this from a command prompt as Administrator:

sc delete [your service name as shown in service.msc e.g moneytransfer]

For example: sc delete moneytransfer

Delete the folder C:\Program Files\BBRTL\moneytransfer\

Find moneytransfer registry keys and delete them:

 HKEY_CLASSES_ROOT\Installer\Products\
 HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\
 HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\EventLog\
 HKEY_LOCAL_MACHINE\System\CurrentControlSet002\Services\
 HKEY_LOCAL_MACHINE\System\CurrentControlSet002\Services\EventLog\
 HKEY_LOCAL_MACHINE\Software\Classes\Installer\Assemblies\ [remove .exe references]
 HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Installer\Folders

These steps have been tested on Windows XP, Windows 7, Windows Vista, Windows Server 2003, and Windows Server 2008.

When are you supposed to use escape instead of encodeURI / encodeURIComponent?

encodeURI() - the escape() function is for javascript escaping, not HTTP.

How to implement Enums in Ruby?

The most idiomatic way to do this is to use symbols. For example, instead of:

enum {
  FOO,
  BAR,
  BAZ
}

myFunc(FOO);

...you can just use symbols:

# You don't actually need to declare these, of course--this is
# just to show you what symbols look like.
:foo
:bar
:baz

my_func(:foo)

This is a bit more open-ended than enums, but it fits well with the Ruby spirit.

Symbols also perform very well. Comparing two symbols for equality, for example, is much faster than comparing two strings.

How do I check to see if a value is an integer in MySQL?

for me the only thing that works is:

CREATE FUNCTION IsNumeric (SIN VARCHAR(1024)) RETURNS TINYINT
RETURN SIN REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';

from kevinclark all other return useless stuff for me in case of 234jk456 or 12 inches

Converting a Uniform Distribution to a Normal Distribution

Here is a javascript implementation using the polar form of the Box-Muller transformation.

/*
 * Returns member of set with a given mean and standard deviation
 * mean: mean
 * standard deviation: std_dev 
 */
function createMemberInNormalDistribution(mean,std_dev){
    return mean + (gaussRandom()*std_dev);
}

/*
 * Returns random number in normal distribution centering on 0.
 * ~95% of numbers returned should fall between -2 and 2
 * ie within two standard deviations
 */
function gaussRandom() {
    var u = 2*Math.random()-1;
    var v = 2*Math.random()-1;
    var r = u*u + v*v;
    /*if outside interval [0,1] start over*/
    if(r == 0 || r >= 1) return gaussRandom();

    var c = Math.sqrt(-2*Math.log(r)/r);
    return u*c;

    /* todo: optimize this algorithm by caching (v*c) 
     * and returning next time gaussRandom() is called.
     * left out for simplicity */
}

How do I dump the data of some SQLite3 tables?

The answer by retracile should be the closest one, yet it does not work for my case. One insert query just broke in the middle and the export just stopped. Not sure what is the reason. However It works fine during .dump.

Finally I wrote a tool for the split up the SQL generated from .dump:

https://github.com/motherapp/sqlite_sql_parser/

Best way to convert pdf files to tiff files

Disclaimer: work for product I am recommending

Atalasoft has a .NET library that can convert PDF to TIFF -- we are a partner of FOXIT, so the PDF rendering is very good.

What are the uses of "using" in C#?

Everything outside the curly brackets is disposed, so it is great to dispose your objects if you are not using them. This is so because if you have a SqlDataAdapter object and you are using it only once in the application life cycle and you are filling just one dataset and you don't need it anymore, you can use the code:

using(SqlDataAdapter adapter_object = new SqlDataAdapter(sql_command_parameter))
{
   // do stuff
} // here adapter_object is disposed automatically

Getting all types in a namespace via reflection

Quite simple

Type[] types = Assembly.Load(new AssemblyName("mynamespace.folder")).GetTypes();
foreach (var item in types)
{
}

Which is the best Linux C/C++ debugger (or front-end to gdb) to help teaching programming?

ddd is a graphical front-end to gdb that is pretty nice. One of the down sides is a classic X interface, but I seem to recall it being pretty intuitive.

How to vertically align elements in a div?

Use this formula, and it will works always without cracks:

_x000D_
_x000D_
#outer {height: 400px; overflow: hidden; position: relative;}_x000D_
#outer[id] {display: table; position: static;}_x000D_
_x000D_
#middle {position: absolute; top: 50%;} /* For explorer only*/_x000D_
#middle[id] {display: table-cell; vertical-align: middle; width: 100%;}_x000D_
_x000D_
#inner {position: relative; top: -50%} /* For explorer only */_x000D_
/* Optional: #inner[id] {position: static;} */
_x000D_
<div id="outer">_x000D_
  <div id="middle">_x000D_
    <div id="inner">_x000D_
      any text_x000D_
      any height_x000D_
      any content, for example generated from DB_x000D_
      everything is vertically centered_x000D_
    </div>_x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

How to get the file path from HTML input form in Firefox 3

This is an example that could work for you if what you need is not exactly the path, but a reference to the file working offline.

http://www.ab-d.fr/date/2008-07-12/

It is in french, but the code is javascript :)

This are the references the article points to: http://developer.mozilla.org/en/nsIDOMFile http://developer.mozilla.org/en/nsIDOMFileList

How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?

The operator == casts between two different types if they are different, while the === operator performs a 'typesafe comparison'. That means that it will only return true if both operands have the same type and the same value.

Examples:

1 === 1: true
1 == 1: true
1 === "1": false // 1 is an integer, "1" is a string
1 == "1": true // "1" gets casted to an integer, which is 1
"foo" === "foo": true // both operands are strings and have the same value

Warning: two instances of the same class with equivalent members do NOT match the === operator. Example:

$a = new stdClass();
$a->foo = "bar";
$b = clone $a;
var_dump($a === $b); // bool(false)

How can I concatenate two arrays in Java?

I've recently fought problems with excessive memory rotation. If a and/or b are known to be commonly empty, here is another adaption of silvertab's code (generified too):

private static <T> T[] concatOrReturnSame(T[] a, T[] b) {
    final int alen = a.length;
    final int blen = b.length;
    if (alen == 0) {
        return b;
    }
    if (blen == 0) {
        return a;
    }
    final T[] result = (T[]) java.lang.reflect.Array.
            newInstance(a.getClass().getComponentType(), alen + blen);
    System.arraycopy(a, 0, result, 0, alen);
    System.arraycopy(b, 0, result, alen, blen);
    return result;
}

Edit: A previous version of this post stated that array re-usage like this shall be clearly documented. As Maarten points out in the comments it would in general be better to just remove the if statements, thus voiding the need for having documentation. But then again, those if statements were the whole point of this particular optimization in the first place. I'll leave this answer here, but be wary!

How to match all occurrences of a regex

Using scan should do the trick:

string.scan(/regex/)

How to Truncate a string in PHP to the word closest to a certain number of characters?

This will return the first 200 characters of words:

preg_replace('/\s+?(\S+)?$/', '', substr($string, 0, 201));

Visual Studio opens the default browser instead of Internet Explorer

In the Solution Explorer, right-click any ASPX page and select "Browse With" and select IE as the default.

Note... the same steps can be used to add Google Chrome as a browser option and to optionally set it as the default browser.

What and where are the stack and heap?

What is a stack?

A stack is a pile of objects, typically one that is neatly arranged.

Enter image description here

Stacks in computing architectures are regions of memory where data is added or removed in a last-in-first-out manner.
In a multi-threaded application, each thread will have its own stack.

What is a heap?

A heap is an untidy collection of things piled up haphazardly.

Enter image description here

In computing architectures the heap is an area of dynamically-allocated memory that is managed automatically by the operating system or the memory manager library.
Memory on the heap is allocated, deallocated, and resized regularly during program execution, and this can lead to a problem called fragmentation.
Fragmentation occurs when memory objects are allocated with small spaces in between that are too small to hold additional memory objects.
The net result is a percentage of the heap space that is not usable for further memory allocations.

Both together

In a multi-threaded application, each thread will have its own stack. But, all the different threads will share the heap.
Because the different threads share the heap in a multi-threaded application, this also means that there has to be some coordination between the threads so that they don’t try to access and manipulate the same piece(s) of memory in the heap at the same time.

Which is faster – the stack or the heap? And why?

The stack is much faster than the heap.
This is because of the way that memory is allocated on the stack.
Allocating memory on the stack is as simple as moving the stack pointer up.

For people new to programming, it’s probably a good idea to use the stack since it’s easier.
Because the stack is small, you would want to use it when you know exactly how much memory you will need for your data, or if you know the size of your data is very small.
It’s better to use the heap when you know that you will need a lot of memory for your data, or you just are not sure how much memory you will need (like with a dynamic array).

Java Memory Model

Enter image description here

The stack is the area of memory where local variables (including method parameters) are stored. When it comes to object variables, these are merely references (pointers) to the actual objects on the heap.
Every time an object is instantiated, a chunk of heap memory is set aside to hold the data (state) of that object. Since objects can contain other objects, some of this data can in fact hold references to those nested objects.

How to convert local time string to UTC?

In python3:

pip install python-dateutil

from dateutil.parser import tz

mydt.astimezone(tz.gettz('UTC')).replace(tzinfo=None) 

A regex for version number parsing

Specifying XSD elements:

<xs:simpleType>
    <xs:restriction base="xs:string">
        <xs:pattern value="[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}(\..*)?"/>
    </xs:restriction>
</xs:simpleType>

Is it possible to print a variable's type in standard C++?

Don't forget to include <typeinfo>

I believe what you are referring to is runtime type identification. You can achieve the above by doing .

#include <iostream>
#include <typeinfo>

using namespace std;

int main() {
  int i;
  cout << typeid(i).name();
  return 0;
}

How do I kill a VMware virtual machine that won't die?

If you're on linux then you can grab the guest processes with

ps axuw | grep vmware-vmx

As @Dubas pointed out, you should be able to pick out the errant process by the path name to the VMD

Where do I find the current C or C++ standard documents?

The actual standards documents may not be the most useful. Most compilers do not fully implement the standards and may sometimes actually conflict. So the compiler documentation that you would already have will be more useful. Additionally, the documentation will contain platform-specific remarks and notes on any caveats.

What IDE to use for Python?

Results

Spreadsheet version

spreadsheet screenshot

Alternatively, in plain text: (also available as a a screenshot)

                         Bracket Matching -.  .- Line Numbering
                          Smart Indent -.  |  |  .- UML Editing / Viewing
         Source Control Integration -.  |  |  |  |  .- Code Folding
                    Error Markup -.  |  |  |  |  |  |  .- Code Templates
  Integrated Python Debugging -.  |  |  |  |  |  |  |  |  .- Unit Testing
    Multi-Language Support -.  |  |  |  |  |  |  |  |  |  |  .- GUI Designer (Qt, Eric, etc)
   Auto Code Completion -.  |  |  |  |  |  |  |  |  |  |  |  |  .- Integrated DB Support
     Commercial/Free -.  |  |  |  |  |  |  |  |  |  |  |  |  |  |  .- Refactoring
   Cross Platform -.  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |     
                  +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
Atom              |Y |F |Y |Y*|Y |Y |Y |Y |Y |Y |  |Y |Y |  |  |  |  |*many plugins
Editra            |Y |F |Y |Y |  |  |Y |Y |Y |Y |  |Y |  |  |  |  |  |
Emacs             |Y |F |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |  |  |  |
Eric Ide          |Y |F |Y |  |Y |Y |  |Y |  |Y |  |Y |  |Y |  |  |  |
Geany             |Y |F |Y*|Y |  |  |  |Y |Y |Y |  |Y |  |  |  |  |  |*very limited
Gedit             |Y |F |Y¹|Y |  |  |  |Y |Y |Y |  |  |Y²|  |  |  |  |¹with plugin; ²sort of
Idle              |Y |F |Y |  |Y |  |  |Y |Y |  |  |  |  |  |  |  |  |
IntelliJ          |Y |CF|Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |
JEdit             |Y |F |  |Y |  |  |  |  |Y |Y |  |Y |  |  |  |  |  |
KDevelop          |Y |F |Y*|Y |  |  |Y |Y |Y |Y |  |Y |  |  |  |  |  |*no type inference
Komodo            |Y |CF|Y |Y |Y |Y |Y |Y |Y |Y |  |Y |Y |Y |  |Y |  |
NetBeans*         |Y |F |Y |Y |Y |  |Y |Y |Y |Y |Y |Y |Y |Y |  |  |Y |*pre-v7.0
Notepad++         |W |F |Y |Y |  |Y*|Y*|Y*|Y |Y |  |Y |Y*|  |  |  |  |*with plugin
Pfaide            |W |C |Y |Y |  |  |  |Y |Y |Y |  |Y |Y |  |  |  |  |
PIDA              |LW|F |Y |Y |  |  |  |Y |Y |Y |  |Y |  |  |  |  |  |VIM based
PTVS              |W |F |Y |Y |Y |Y |Y |Y |Y |Y |  |Y |  |  |Y*|  |Y |*WPF bsed
PyCharm           |Y |CF|Y |Y*|Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |*JavaScript
PyDev (Eclipse)   |Y |F |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |Y |  |  |  |
PyScripter        |W |F |Y |  |Y |Y |  |Y |Y |Y |  |Y |Y |Y |  |  |  |
PythonWin         |W |F |Y |  |Y |  |  |Y |Y |  |  |Y |  |  |  |  |  |
SciTE             |Y |F¹|  |Y |  |Y |  |Y |Y |Y |  |Y |Y |  |  |  |  |¹Mac version is
ScriptDev         |W |C |Y |Y |Y |Y |  |Y |Y |Y |  |Y |Y |  |  |  |  |    commercial
Spyder            |Y |F |Y |  |Y |Y |  |Y |Y |Y |  |  |  |  |  |  |  |
Sublime Text      |Y |CF|Y |Y |  |Y |Y |Y |Y |Y |  |Y |Y |Y*|  |  |  |extensible w/Python,
TextMate          |M |F |  |Y |  |  |Y |Y |Y |Y |  |Y |Y |  |  |  |  |    *PythonTestRunner
UliPad            |Y |F |Y |Y |Y |  |  |Y |Y |  |  |  |Y |Y |  |  |  |
Vim               |Y |F |Y |Y |Y |Y |Y |Y |Y |Y |  |Y |Y |Y |  |  |  |
Visual Studio     |W |CF|Y |Y |Y |Y |Y |Y |Y |Y |? |Y |? |? |Y |? |Y |
Visual Studio Code|Y |F |Y |Y |Y |Y |Y |Y |Y |Y |? |Y |? |? |? |? |Y |uses plugins
WingIde           |Y |C |Y |Y*|Y |Y |Y |Y |Y |Y |  |Y |Y |Y |  |  |  |*support for C
Zeus              |W |C |  |  |  |  |Y |Y |Y |Y |  |Y |Y |  |  |  |  |
                  +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
   Cross Platform -'  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |     
     Commercial/Free -'  |  |  |  |  |  |  |  |  |  |  |  |  |  |  '- Refactoring
   Auto Code Completion -'  |  |  |  |  |  |  |  |  |  |  |  |  '- Integrated DB Support
    Multi-Language Support -'  |  |  |  |  |  |  |  |  |  |  '- GUI Designer (Qt, Eric, etc)
  Integrated Python Debugging -'  |  |  |  |  |  |  |  |  '- Unit Testing
                    Error Markup -'  |  |  |  |  |  |  '- Code Templates
         Source Control Integration -'  |  |  |  |  '- Code Folding
                          Smart Indent -'  |  |  '- UML Editing / Viewing
                         Bracket Matching -'  '- Line Numbering

Acronyms used:

 L  - Linux
 W  - Windows
 M  - Mac
 C  - Commercial
 F  - Free
 CF - Commercial with Free limited edition
 ?  - To be confirmed

I don't mention basics like syntax highlighting as I expect these by default.


This is a just dry list reflecting your feedback and comments, I am not advocating any of these tools. I will keep updating this list as you keep posting your answers.

PS. Can you help me to add features of the above editors to the list (like auto-complete, debugging, etc.)?

We have a comprehensive wiki page for this question https://wiki.python.org/moin/IntegratedDevelopmentEnvironments

Submit edits to the spreadsheet

Difference between BYTE and CHAR in column datatypes

One has exactly space for 11 bytes, the other for exactly 11 characters. Some charsets such as Unicode variants may use more than one byte per char, therefore the 11 byte field might have space for less than 11 chars depending on the encoding.

See also http://www.joelonsoftware.com/articles/Unicode.html

How do I set up access control in SVN?

The best way is to set up Apache and to set the access through it. Check the svn book for help. If you don't want to use Apache, you can also do minimalistic access control using svnserve.

Most efficient way to increment a Map value in Java

A little research in 2016: https://github.com/leventov/java-word-count, benchmark source code

Best results per method (smaller is better):

                 time, ms
kolobokeCompile  18.8
koloboke         19.8
trove            20.8
fastutil         22.7
mutableInt       24.3
atomicInteger    25.3
eclipse          26.9
hashMap          28.0
hppc             33.6
hppcRt           36.5

Time\space results:

How to move the cursor word by word in the OS X Terminal

For some reason, my terminal's option+arrow weren't working. To fix this on macOS 10.15.6, I opened the terminal app's preferences, and had to set the bindings.

Option-left = \033b
Option-right = \033e

Keyboard settings in Mac terminal app

For some reason, the option-right I had was set up to be \033f. Now that it's fixed, I can freely skip around words in the termianl again.

How can I view the allocation unit size of a NTFS partition in Vista?

Open an administrator command prompt, and do this command:

fsutil fsinfo ntfsinfo [your drive]

The Bytes Per Cluster is the equivalent of the allocation unit.

Converting an integer to a hexadecimal string in Ruby

You can give to_s a base other than 10:

10.to_s(16)  #=> "a"

Note that in ruby 2.4 FixNum and BigNum were unified in the Integer class. If you are using an older ruby check the documentation of FixNum#to_s and BigNum#to_s

Is there a macro to conditionally copy rows to another worksheet?

If this is just a one-off exercise, as an easier alternative, you could apply filters to your source data, and then copy and paste the filtered rows into your new worksheet?

How do I use WPF bindings with RelativeSource?

I created a library to simplify the binding syntax of WPF including making it easier to use RelativeSource. Here are some examples. Before:

{Binding Path=PathToProperty, RelativeSource={RelativeSource Self}}
{Binding Path=PathToProperty, RelativeSource={RelativeSource AncestorType={x:Type typeOfAncestor}}}
{Binding Path=PathToProperty, RelativeSource={RelativeSource TemplatedParent}}
{Binding Path=Text, ElementName=MyTextBox}

After:

{BindTo PathToProperty}
{BindTo Ancestor.typeOfAncestor.PathToProperty}
{BindTo Template.PathToProperty}
{BindTo #MyTextBox.Text}

Here is an example of how method binding is simplified. Before:

// C# code
private ICommand _saveCommand;
public ICommand SaveCommand {
 get {
  if (_saveCommand == null) {
   _saveCommand = new RelayCommand(x => this.SaveObject());
  }
  return _saveCommand;
 }
}

private void SaveObject() {
 // do something
}

// XAML
{Binding Path=SaveCommand}

After:

// C# code
private void SaveObject() {
 // do something
}

// XAML
{BindTo SaveObject()}

You can find the library here: http://www.simplygoodcode.com/2012/08/simpler-wpf-binding.html

Note in the 'BEFORE' example that I use for method binding that code was already optimized by using RelayCommand which last I checked is not a native part of WPF. Without that the 'BEFORE' example would have been even longer.

Adding a guideline to the editor in Visual Studio

The registry path for Visual Studio 2008 is the same, but with 9.0 as the version number:

HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\9.0\Text Editor

Setting the default ssh key location

man ssh gives me this options would could be useful.

-i identity_file Selects a file from which the identity (private key) for RSA or DSA authentication is read. The default is ~/.ssh/identity for protocol version 1, and ~/.ssh/id_rsa and ~/.ssh/id_dsa for pro- tocol version 2. Identity files may also be specified on a per- host basis in the configuration file. It is possible to have multiple -i options (and multiple identities specified in config- uration files).

So you could create an alias in your bash config with something like

alias ssh="ssh -i /path/to/private_key"

I haven't looked into a ssh configuration file, but like the -i option this too could be aliased

-F configfile Specifies an alternative per-user configuration file. If a configuration file is given on the command line, the system-wide configuration file (/etc/ssh/ssh_config) will be ignored. The default for the per-user configuration file is ~/.ssh/config.

Curl command line for consuming webServices?

Wrong. That doesn't work for me.

For me this one works:

curl 
-H 'SOAPACTION: "urn:samsung.com:service:MainTVAgent2:1#CheckPIN"'   
-X POST 
-H 'Content-type: text/xml'   
-d @/tmp/pinrequest.xml 
192.168.1.5:52235/MainTVServer2/control/MainTVAgent2

Remove spaces from std::string in C++

If you want to do this with an easy macro, here's one:

#define REMOVE_SPACES(x) x.erase(std::remove(x.begin(), x.end(), ' '), x.end())

This assumes you have done #include <string> of course.

Call it like so:

std::string sName = " Example Name ";
REMOVE_SPACES(sName);
printf("%s",sName.c_str()); // requires #include <stdio.h>

How do I call a SQL Server stored procedure from PowerShell?

Consider calling osql.exe (the command line tool for SQL Server) passing as parameter a text file written for each line with the call to the stored procedure.

SQL Server provides some assemblies that could be of use with the name SMO that have seamless integration with PowerShell. Here is an article on that.

http://www.databasejournal.com/features/mssql/article.php/3696731

There are API methods to execute stored procedures that I think are worth being investigated. Here a startup example:

http://www.eggheadcafe.com/software/aspnet/29974894/smo-running-a-stored-pro.aspx

How can I extract a predetermined range of lines from a text file on Unix?

You could use 'vi' and then the following command:

:16224,16482w!/tmp/some-file

Alternatively:

cat file | head -n 16482 | tail -n 258

EDIT:- Just to add explanation, you use head -n 16482 to display first 16482 lines then use tail -n 258 to get last 258 lines out of the first output.

What's wrong with foreign keys?

They can make deleting records more cumbersome - you can't delete the "master" record where there are records in other tables where foreign keys would violate that constraint. You can use triggers to have cascading deletes.

If you chose your primary key unwisely, then changing that value becomes even more complex. For example, if I have the PK of my "customers" table as the person's name, and make that key a FK in the "orders" table", if the customer wants to change his name, then it is a royal pain... but that is just shoddy database design.

I believe the advantages in using fireign keys outweighs any supposed disadvantages.

Why not use tables for layout in HTML?

I'd like to add that div-based layouts are easer to mantain, evolve, and refactor. Just some changes in the CSS to reorder elements and it is done. From my experience, redesign a layout that uses tables is a nightmare (more if there are nested tables).

Your code also has a meaning from a semantic point of view.

ORA-03113: end-of-file on communication channel after long inactivity in ASP.Net app

This error message can be thrown in the application logs when the actual issue is that the oracle database server ran out of space.

After correcting the space issue, this particular error message disappeared.

Before and After Suite execution hook in jUnit 4.x

A colleague of mine suggested the following: you can use a custom RunListener and implement the testRunFinished() method: http://junit.sourceforge.net/javadoc/org/junit/runner/notification/RunListener.html#testRunFinished(org.junit.runner.Result)

To register the RunListener just configure the surefire plugin as follows: http://maven.apache.org/surefire/maven-surefire-plugin/examples/junit.html section "Using custom listeners and reporters"

This configuration should also be picked by the failsafe plugin. This solution is great because you don't have to specify Suites, lookup test classes or any of this stuff - it lets Maven to do its magic, waiting for all tests to finish.

How to list the tables in a SQLite database file that was opened with ATTACH?

Via a union all, combine all tables into one list.

select name
from sqlite_master 
where type='table'

union all 

select name 
from sqlite_temp_master 
where type='table'

How do I check whether a file exists without exceptions?

If the reason you're checking is so you can do something like if file_exists: open_it(), it's safer to use a try around the attempt to open it. Checking and then opening risks the file being deleted or moved or something between when you check and when you try to open it.

If you're not planning to open the file immediately, you can use os.path.isfile

Return True if path is an existing regular file. This follows symbolic links, so both islink() and isfile() can be true for the same path.

import os.path
os.path.isfile(fname) 

if you need to be sure it's a file.

Starting with Python 3.4, the pathlib module offers an object-oriented approach (backported to pathlib2 in Python 2.7):

from pathlib import Path

my_file = Path("/path/to/file")
if my_file.is_file():
    # file exists

To check a directory, do:

if my_file.is_dir():
    # directory exists

To check whether a Path object exists independently of whether is it a file or directory, use exists():

if my_file.exists():
    # path exists

You can also use resolve(strict=True) in a try block:

try:
    my_abs_path = my_file.resolve(strict=True)
except FileNotFoundError:
    # doesn't exist
else:
    # exists

Convert DOS line endings to Linux line endings in Vim

Change the line endings in the view:

:e ++ff=dos
:e ++ff=mac
:e ++ff=unix

This can also be used as saving operation (:w alone will not save using the line endings you see on screen):

:w ++ff=dos
:w ++ff=mac
:w ++ff=unix

And you can use it from the command-line:

for file in *.cpp
do 
    vi +':w ++ff=unix' +':q' "$file"
done

Can you use Microsoft Entity Framework with Oracle?

DevArt's OraDirect provider now supports entity framework. See http://devart.com/news/2008/directs475.html

svn over HTTP proxy

In /etc/subversion/servers you are setting http-proxy-host, which has nothing to do with svn:// which connects to a different server usually running on port 3690 started by svnserve command.

If you have access to the server, you can setup svn+ssh:// as explained here.

Update: You could also try using connect-tunnel, which uses your HTTPS proxy server to tunnel connections:

connect-tunnel -P proxy.company.com:8080 -T 10234:svn.example.com:3690

Then you would use

svn checkout svn://localhost:10234/path/to/trunk

How do I use sudo to redirect output to a location I don't have permission to write to?

A trick I figured out myself was

sudo ls -hal /root/ | sudo dd of=/root/test.out

Why is using the JavaScript eval function a bad idea?

It's generally only an issue if you're passing eval user input.

Does C# have an equivalent to JavaScript's encodeURIComponent()?

Try Server.UrlEncode(), or System.Web.HttpUtility.UrlEncode() for instances when you don't have access to the Server object. You can also use System.Uri.EscapeUriString() to avoid adding a reference to the System.Web assembly.

How do I upload a file to an SFTP server in C# (.NET)?

Maybe you can script/control winscp?

Update: winscp now has a .NET library available as a nuget package that supports SFTP, SCP, and FTPS

What’s the best way to reload / refresh an iframe?

If using jQuery, this seems to work:

$('#your_iframe').attr('src', $('#your_iframe').attr('src'));

I hope it's not too ugly for stackoverflow.

Select current date by default in ASP.Net Calendar control

I was trying to make the calendar selects a date by default and highlights it for the user. However, i tried using all the options above but i only managed to set the calendar's selected date.

protected void Page_Load(object sender, EventArgs e)
    Calendar1.SelectedDate = DateTime.Today;
}

the previous code did NOT highlight the selection, although it set the SelectedDate to today.

However, to select and highlight the following code will work properly.

protected void Page_Load(object sender, EventArgs e)
{
    DateTime today = DateTime.Today;
    Calendar1.TodaysDate = today;
    Calendar1.SelectedDate = Calendar1.TodaysDate;
}

check this link: http://msdn.microsoft.com/en-us/library/8k0f6h1h(v=VS.85).aspx

How can I get Git to follow symlinks?

On MacOS (I have Mojave/ 10.14, git version 2.7.1), use bindfs.

brew install bindfs

cd /path/to/git_controlled_dir

mkdir local_copy_dir

bindfs </full/path/to/source_dir> </full/path/to/local_copy_dir>

It's been hinted by other comments, but not clearly provided in other answers. Hopefully this saves someone some time.

How do I ignore files in Subversion?

Use the command svn status on your working copy to show the status of files, files that are not yet under version control (and not ignored) will have a question mark next to them.

As for ignoring files you need to edit the svn:ignore property, read the chapter Ignoring Unversioned Items in the svnbook at http://svnbook.red-bean.com/en/1.5/svn.advanced.props.special.ignore.html. The book also describes more about using svn status.

How do I create a folder in VB if it doesn't exist?

Just do this:

        Dim sPath As String = "Folder path here"
    If (My.Computer.FileSystem.DirectoryExists(sPath) = False) Then
        My.Computer.FileSystem.CreateDirectory(sPath + "/<Folder name>")
    Else
        'Something else happens, because the folder exists
    End If

I declared the folder path as a String (sPath) so that way if you do use it multiple times it can be changed easily but also it can be changed through the program itself.

Hope it helps!

-nfell2009