In the case of linked circular list you need to add some checks to avoid memory corruption.

Full example (compiled OK with GCC 8.x)

#include <iostream>
#include <cstdlib>

struct Node
{
    Node(Node* prev, int val)
        : prev(prev), next(NULL), value(val)
    { }
    Node *prev, *next;
    int value;
};

void clear_list(Node …

Hash indexes are used as entry points for memory-optimized tables; both features were introduced in SQL Server 2014. Let's look at index performance in scenario "key-value store".

Scenario and environment

The table stores a significant volume (about 10 millions rows) of pairs key-value. The key is of integer type and …

Unfortunately, SQL Server doesn't have a function like frac to extract the fractional part of number. The method is to subtract the integer part from the origin value.

DECLARE @n1 float, @n2 float, @n3 float;
SELECT @n1 = 123.456, @n2 = 234.567, @n3 = 456.789;
SELECT @n1 - round(@n1, 0 …

Collection of methods to generate random string in a single SQL statement

M1: Recursive string concatenation

On SQL Server the method is limited by 100 characters because of CTE recursion level limitation. The method has the performance issues when using in loops/joins because the table always have 100 rows …

This small example shows how to synchronize the data of two tables using the MERGE statement

CREATE TABLE table1 (id int NOT NULL PRIMARY KEY, str_value nvarchar(50));
CREATE TABLE table2 (id int NOT NULL PRIMARY KEY, str_value nvarchar(50));
GO
INSERT INTO table1 (id, str_value) VALUES (1, 'Value 1 …

The small test program shows how memory and file I/O operations can be accelerated using multiple threads.

Scenario

The program uses

• N threads (1 means a single thread)
• X bytes of memory to allocate a huge block (255 MB by default)
• M files to dump some huge memory block …

Notepad++ can count LOC (lines of code) of source files and give you the estimation of code size.

Press Ctrl+Shift+F shortcut to start "Find in files" dialog. Select "regular expression" search mode and start it.

Some regular expressions:

• \S+\s*$ -- all non-empty lines
• ^\s*$ -- only empty (white-space) lines …

How to set classic background color in Windows 10?

• Right click on desktop and select "Personalize" menu
• Set "Background" option to "Solid color"
• Click on "+ custom color" button
• Click on "More"
• Check that "RGB" is set
• Enter "#336EA5" and click "Done" button

That's all.

"Programming with databases" (both printed version and Kindle e-book) is the translated and revised Second Edition of my previous book published in 2015.

This book covers various stages of software development and practical cases of the programming with database management systems. You find different recommendations on the choices of the …

Delphi case

Delphi supports interfaces natively. Any variable of variant type can store an interface like any allowed data types.

program IntfDelphi;

{$APPTYPE CONSOLE}
{$R *.res}

uses
  Classes, SysUtils, Variants;

type
  ITest = interface(IInterface)
    ['{BEDC5E17-2C40-4F7C-8C78-34448F5CE146}']
    procedure Foo(const Msg: string);
  end;

  TestImpl = class(TInterfacedObject, ITest)
  public
    procedure Foo(const Msg …