UFO Trick

Pesti Meló

Bunkos Tesók - Bolyai Club

Hugh Laurie's song for America

The OMG Cat / Az "Óh, jajj, Istenem!" macska

Original / Eredeti

~ sees car accident / ~ autóbalesetet lát

OMG Cat sees Car Accident - watch more funny videos

Ruby is not good at comments

Problem

Imagine that you are hard-coding some long list into your Ruby code and you need to

• wrap the long line into multiple lines
• comment on some items

Let's look at the 1st goal (imagine a lot longer list)!

@@import_fields = [ \
    "Name" \
    , "Organization" \
    , "Role" \
    , "Internal ID" \
];

Pretty ugly, because the statement separator is the newline and you should escape it. But doable. Let's move on!

Completing the second goal is not possible. The only commenting option is the line-commenting which is starts with the # sign and ends when the line ends. If you place the comment before the backslash (\), your interpreter will not detect the newline escaper backslash. If you place the comment after it, then it stops being a newline escaper.

Nonexistent solutions

• The Ruby guys failed to add statement separators / terminators to the language and that remains this way. I think the intention was to make life easier, but I believe they made it harder. Someone someday may enlighten me.
• They should introduce block comments. It would be backward compatible and would make the World a better place.
• Or they should detect the newline escaping after the # sign.

Workaround

@@import_fields = []
@@import_fields << "Name"
@@import_fields << "Organization" # Some clever saying about this field
@@import_fields << "Role"
@@import_fields << "Internal ID" # And some eternal wisdom about this

If you know a better way, don't hesitate to tell me!

Indent with TABs, format with spaces

TABs vs spaces

1st: Visible with

They say that TABs are rendered differently by different softwares and devices. I cannot accept that. Read on.

UNICODE 2.0 released in year 1996. In around 2001 people wanted to kill me because I used UTF-8 characters on IRC, and they argued that their [not so good] software cannot render them correctly. I ignored them. Their [not so good] software became advanced, their minds became open.

Editors and devices where the visible width of TAB characters cannot be adjusted are not so good. TAB is not a new invention at all.

2nd: Formatting

TABs are not for formatting. They are only for indenting.

int·main()
{
→   printf("Hello·%s!\n",·//·I·like·to·move·it,
→   ·······"World");······//·move·it.
→   return 0;
}

If you want to graphically align something then you should use SPACES. If you are expressing the depth of control, then you should use TAB. The above code will maintain it's visual, see:

int·main()
{
→   {·//·Ad-hoc·block·begin
→   →   printf("Hello·%s!\n",·//·I·like·to·move·it,
→   →   ·······"World");······//·move·it.
→   →   return·0;
→   }·//·Ad-hoc·block·end
}

3rd: Freedom

See what happens when visible with of TAB is set to 8, because someone may like it that way:

int·main()
{
→       {·//·Ad-hoc·block·begin
→       →       printf("Hello·%s!\n",·//·I·like·to·move·it,
→       →       ·······"World");······//·move·it.
→       →       return·0;
→       }·//·Ad-hoc·block·end
}

The hairdo is still tight.

What if someone's favorite visual TAB size is 2?

int·main()
{
→ {·//·Ad-hoc·block·begin
→ → printf("Hello·%s!\n",·//·I·like·to·move·it,
→ → ·······"World");······//·move·it.
→ → return·0;
→ }·//·Ad-hoc·block·end
}

The hairdo is still tight.

4th: Symbolism

From my heart: http://www.mail-archive.com/vim_use@googlegroups.com/msg18895.html

Favorite part: ... tabs for leading indent, spaces everywhere else. I prefer this strategy for the same reason I prefer to use symbolic names for constants, rather than embedding numeric literals throughout my source code ...

Traffic jam experiment / Dugó kisérlet

Stephen Fry & Hugh Laurie

Régi cucc, ami csak nekem új. Dr House egy másik élete.



Old stuff which is new for me. Another life of Doctor House.

Villamosos üldözés / Tram pushuit

Have a good evening!

In current days, while the criminal acts are spreading, the daredevils of the gangland invent newer and newer ways to deliver their deeds.

The following police recording proofs that criminals are not picky about the vehicles they use during robbery.

Happy debugging

#define TRUE FALSE /* Happy debugging, suckers! */

Editing JPEG DPI without resampling

The title is the naive search term for a problem. The good search term - or Google power phrase - is Exif editor. The best of the results which simply solves the problem is the Exif Pilot on an Exif editors page. Enjoy!

P.S.: I decided to publicate the fruit of every hard and exhausting search on this blog. Maybe it is not good for the regular visitor, but I'm sure it helps the Universe in general. :-)

--- Hungarian version

JPEG DPI szerkesztés: Ez a jó neked: Exif Pilot az Exif editors oldalról.

Welcome to Ruby

myString = "Welcome to JavaScript!"
=> "Welcome to JavaScript!"

myString[8..20]= "Ruby"
=> "Ruby"

puts myString
=> "Welcome Ruby!"

Monorail cat / Mágnesvasút macska*

→ Catmas blog

*Korrekció: Egysínű macska. Könszönet Anonymousnak! :-)

LOLCODE

~ is an esoteric programming language inspired by the language expressed in examples of the lolcat Internet meme. The language was created in 2007 by Adam Lindsay, researcher at the Computing Department of Lancaster University.

The language is not clearly defined in terms of operator priorities and correct syntax, but several functioning interpreters and compilers already exist. The language has been proven Turing-complete.

-- Wikipedia

Examples

• Hello World!
  

  HAI
  CAN HAS STDIO?
  VISIBLE "HAI WORLD!"
  KTHXBYE
  

• Print numbers from 1 to ROOF.
  

  HAI
  CAN HAS STDIO?
  I HAS A ROOF, I HAS A VAR ITZ 0
  GIMMEH ROOF BTW U R IN CONTROL
  IM IN YR LOOP
          UP VAR!!1
          IZ VAR BIGGER THAN ROOF? KTHXBYE
          VISIBLE SMOOSH VAR AN ":)" MKAY
  IM OUTTA YR LOOP
  KTHXBYE
  

→ lolcode.com

Lagoa Multiphysics 1.0

Lagoa Multiphysics 1.0 - Teaser from Thiago Costa on Vimeo.

Paul, the octopus, circa 1942

(Uknown source, from a chat)
(Ismeretlen forrásból, egy csetről)

Publishing detailed error messages

As an opposition to "Hiding error details". On the input of [Posa1996]¹ page 43 (Architectural patterns (2) / Layers (2.2) / Implementation / 10):

Design an error handling strategy. Error handling can be rather expensive for layered architectures with respect to processing time and, notably, programming effort. An error can either be handled in the layer where it occurred or be passed to the next higher layer. In the latter case, the lower layer must transform the error into an error description meaningful to the higher layer. As a rule of thumb, try to handle errors at the lowest layer possible. This prevents higher layers from being swamped with many different errors and voluminous error-handling code. As a minimum, try to condense similar error types into more general error types, and only propagate these more general errors. If you do not do this, higher layers can be confronted with error messages that apply to lower-level abstractions that the higher layer does not understand. And who hasn't seen totally cryptic error messages being popped up to the highest layer of all - the user?

I have to strongly disagree with the author on that point. It is far more worse if the highest layer of all gets an error like "Error." without any details. The error message should be as detailed as possible. Do not be confused! That does not mean that higher layers should not handle these errors in a grouped manner. For example if a file transfer fails on any reason the program logic should abort the transaction, whatever the reason of the failure is, so the so called voluminous error-handling code can be avoided. Not handling but publishing the details of the error can help the user understand and solve the problem. Making distinction between "Directory not found.", "Drive not ready.", and "Permission denied." is very useful at the level of the user (or customer care, product support line, developer, whoever).

Testing, debugging and user support can be a horror without detailed error messages. It can be counted in serious amount of money. If the user does understand the error message then it is an instant win for the user himself/herself and for the customer care both. If he/she doesn't understand then he/she has something to tell at official and unofficial support forums which will bring the solution closer. It is a win-win decision to keep the error messages detailed.

And again, it does not contradict the "keep the volume of error-handling code low" principle. Handling ≠ publishing.

→ ¹: [Posa1996] Frank Buschmann et al.: Pattern-oriented software architecture, Volume 1: A system of patterns; © 1996 John Wiley and sons

The most useless machine / A leghaszontalanabb gép

Processing.org

Processing is an open source programming language and environment for people who want to create images, animations, and interactions. Initially developed to serve as a software sketchbook and to teach fundamentals of computer programming within a visual context, Processing also has evolved into a tool for generating finished professional work. Today, tens of thousands of students, artists, designers, researchers, and hobbyists who use Processing for learning, prototyping, and production.

→ processing.org

The apropo for posting this is that I regenerated my toy applets that I wrote in this environment.

→ My graphic applets, with source code. Enjoy!

Silver needle in the Skype

by Philippe BIONDI and Fabrice DESCLAUX
BlackHat Europe, March 2nd and 3rd, 2006

→ skype_BHEU06.pdf

Repost of a synsecblog entry.

If you can repeat their results you rock!!!

Codility (x)

Automated tests of programming skills.

Codility saves time of software talent recruiters by filtering out job candidates who cannot write correct programs.

Codility administers short programming tests and checks whether solutions are rock solid.

Our customers filter out up to 90% of candidates. Less wasted time. Better hires.

→ http://codility.com/

Carrot horror / répa horror

Weekend carrot horror by trn from Gabor Penoff on Vimeo.

Bicycle for floods / Árvízibicikli

amphibious / kétéltű

→ @index.hu

Java 4-ever - JavaZone trailer

(Removed due to copyright claims. Another source follows.)

French and Italian soccer / Francia és olasz foci

--- English version follows

A francia és az olasz csapat tagjai tegnap közösen meglátogattak egy fokvárosi árvaházat. Szívszorító volt látni a szomorú kis arcukat és a reménytelenséget – nyilatkozta a 6 éves Dzsamal.

--- English version

The members of the French and Italian soccer teams joined together and visited a shelter for orphaned children in Cape Town. It was heart-smothering seeing their little sad faces and the hopelessness – explained Jamal the 6 years old boy.

Vuvuzela for eva'

Vuvuzela for ever

→ @index.hu

My penis is too short / A péniszem túl rövid

--- English version follows

Azt mondta a rendszer, hogy meg kell adnom egy jelszót. Azt mondtam "faszom". Mire a rendszer közölte, hogy túl rövid.

Megkérdeztem egy kollégámat, hogy ilyenkor mit kell csinálni. Azt mondta, hogy elfelejtettem beírni a méretét, úgy mint "faszom45". Működött.

--- English version

The system said that give it a password. I typed "mydick". The system said it is too short.

I asked a colleague what to do. He said that I have to type in the size, like "mydick45". It worked.

n over k

long long NOverK(int n, int k)
{
    if(k > n >> 1)
        k = n - k;
    long long ret = 1;
    for(int i = 1; i<=k; ++i,--n)
        (ret *= n) /= i;
    return ret;
}

What the hex / Milyen színű ?

http://yizzle.com/whatthehex/

Surface of the Earth / A Föld felszíne

http://graphjam.com/2010/06/14/funny-graphs-surface-earth/

I'm on a horse

Gibbets (game / játék)

Save the hanging people!
Mentsd meg a felakasztott embereket!



→ http://www.notdoppler.com/gibbets.php

UPDATE: It has a second episode.
FRISSÍTÉS: Van második része is.

→ http://www.notdoppler.com/gibbets2.php

C++: Class vs Struct (clarification)

Classes and structures are the same thing in C++ except that the struct's default visibility is public, the class' is private. To highlight the equivalence: struct can have member functions, constructors, overloaded operators, virtual member functions, private members. Classes can have public data members. It is really just about the default visibility of members.

Let's see equivalent examples, let's talk about the philosophy later...

struct Vector {
    double x,y;
};

class Vector {
public:
    double x,y;
};

and

class Vector {
public:
    Vector(double x_, double _y);
    Vector& SetXY(double x_,double y_);
    double GetX() const;
    double GetY() const;
    //...
private:
    double x,y;
};

struct Vector {
    Vector(double x_, double _y);
    Vector& SetXY(double x_,double y_);
    double GetX() const;
    double GetY() const;
    //...
private:
    double x,y;
};

In my opinion class's default visibility is not very useful because we used to start the class definition with the public members to ease the interpretation of it for the users of our class.

The big difference is in the intent of the declaration. If we want to create a composite behavior-less data unit that is passed around, then we should use the struct keyword so the reader will know what's going on. If you want to create an object which fulfills an abstract concept and has a behavior, then you should define a class.

IMPORTANT: If you use class you should really take care about the basic requirements like hiding data members (making them private or protected in order to maintain principle of local responsibility), providing type-invariant safe public methods, disabling copy semantics if not needed explicitly, and so on ...

C++: The static keyword (clarification)

The static keyword can have three different meaning depending on the context.

Static function or variable

The variable or function name will not be propagated for the linker, that means that this variable or function will be available only in it's compilation unit. This feature is rarely used, only if we want to hide something explicitly from other compilation units.

static int MySecretFunction(){ /* ... */ }
static int MY_SECRET_VARIABLE = 7; // You should give a starting value

Static variable in a function

int Summarize(int next)
{
    static int sum = 0;
    sum += next;
    return sum
}

The static variable in a function is initialized at the first time when the function is called. WARNING: Using this feature is not thread-safe in C++. In C++0x you will have the opportunity to write

thread_local static int sum = 0;

which creates a global variable in the function's scope for each thread.

Static class members

Class member functions (methods) can be static or non-static. Non-static members are bound to the objects of the class, static members are not bound to the objects but are somehow related to the class. Study example:

// matrix.h:
class Matrix {
public:
    Matrix(int n_, int m_); // Constructor
    Matrix& MultiplyByNumber(double lambda); // Non-static member function
    static Matrix CreateIdentityMatrix(int n); // Static member function
    // ...
private:
    int n,m; // Non static emember variables
    double *pData; // Non static member variable
    static int serial; // Static member variable
};
// matrix.cpp:
int Matrix::serial = 0;
// ...

Note: You have to provide explicit storage place for the static member variables, that means you have to choose a compilation unit (.cpp file), where you write int Matrix::serial = 0;.
Non-static (or object-) methods can access both static and non-static member functions and variables. Static methods can access only static members. (And of course non-static members of the objects that are around.)

Simple global variables and initialization

// gadget.h:
extern int dontUseGlobalVariablesIfPossible; // "Propagation" in the .h file
// gadget.cpp:
int dontUseGlobalVariablesIfPossible = 0; // Storage place

The initialization of variables in static storage class (simple global variables, static variables, static member variables, but not function's static variables) are done in the order that they are presented inside the compilation unit (see exception below). The order of initialization of two variables in different compilation units is undefined.
The important exception is that primitive types (int, char, pointer, float, double, ...) are initialized upon loading if they are initialized with literals.

int x = 0; // Load time, practically before "everything"
int y = f(); // Simply before main() based on the rules above.

C++: References and pointers (clarification)

pointer

A pointer refers directly to (or "points to") another value stored elsewhere in the computer memory using its address. It can be also interpreted as a pointer to many objects, depending on the semantics of the usage.

reference

Is a pointer with some (useful) restrictions and a reliefs. It's value can be set only once (at declaration) and it can point only to one object. The relief is that you don't have to apply any syntax for dereferencing. Another benefit is that you know that the area pointed by a reference does not have to be freed by you.

Pointer examples

int array[10]; // Array with 10 elements allocated on the stack
*array = 5; // Set the zeroth element to 5
*(array+1) = 6; // Set the first element to 6
array[2] = 7; // Set the second element to 7

int *array2 = new int[10]; // Array allocated on the heap
*array2 = 5; // Set the zeroth element to 5
*(array2+1) = 6; // Set the first element to 6
array2[2] = 7; // Set the second element to 7
delete[] array2; // Freeing allocation

int *p = array+3; // Create a pointer to the 3rd element
*p = 8; // Set it to 8

char s1[] = {'H','E','L','L','O','!',0}; // Char array on stack (terminated by zero)
char s2[] = "HELLO!"; // Char array on stack (terminated by zero)
const char *s3 = "HELLO!"; // Pointer to string literal. "const" because you do not want to change a literal, do you?

• In the first case you don't really have a pointer that is stored anywhere. Handling of aggregated arrays (on stack or in a class/struct) is presented with pointer-syntax.
• In the second case you really have a pointer on the stack that points to the allocated area which is on the heap.

To demonstrate the difference between pointers and pseudo pointers:

++array; // Will not compile
++array2; // Will incrase the array2 pointer by one
// (it will point to the 1st element in the array - not the 0th)

Note that you still have to call delete[] with a pointer that points to the 0th element!!! Something like

delete[] (array2-1);

Reference examples

Reference typed parameter

std::string ReverseText(const std::string& text)
{
    size_t len = text.size();
    std::string ret(len,'\0');
    for(int i=0; i<len; ++i)
    {
        ret.at(i) = text.at(len-1-i);
    }
    return ret; // We love "named return value optimization"
}

Note: ret.at(i) returns a reference to the i-th character of the string.

• The parameter's value is not copied, just a pointer to it.
• You don't have to use pointer syntax like (*text).size() (or text->size()), you can use text.size() conveniently
• You don't have to test for NULL pointer. The user of the function can clearly see that he cannot pass a NULL pointer, that he/she must provide this parameter.

Invocation:

std::string s("Heavy Metal music");
std::cout << ReverseText(s) << std::endl;

Aliasing

A real life example would involve more complex concepts than the aliasing itself. It is rarely used, but very useful when needed. So let's see a l'art pour l'art teaching example!

unsigned int LargestCommonDivider(unsigned int a, unsigned int b)
{
    while(a!=b)
    {
        unsigned int &greater(a>b?a:b);
        unsigned int &smaller(a>b?b:a);
        greater -= smaller;
    }
    return a;
}

• Let's see the usefulness and necessity of "functional programming minded" operator ?: here!
• The a and b variables are copies of the parameters given at the place of invocation, they can be used as ordinary local variables (which they are in reality).

See also initializer list.

Opening beer with a helicopter / Sörnyitás helikopterrel

That's the way this is done.
Így kell csinálni.

Gully at Guatemala / Guatemalai víznyelő

Pictures without boundaries
(Some of them are boring, but there are some treasure there)

Képek határok nélkül
(Néhányuk uncsi, de van pár igazi gyöngyszem)



→ @ index.hu

The Bluesmaker

http://www.thebluesmaker.com/

The cutting edge of pointless being

Az értelmetlenség csúcsteljesítménye



From here (innen): http://kerekagy.blog.hu/2009/12/02/fitnesz

Kinderkreis: Danse Gooshers!

Critical Mass { with small people , kis emberkékkel }

Ball trick / Labda trükk

C++: Initializing containers with compile time list of data

template <typename T, size_t size>
void FillSet(std::set<T>& target, const T (&list)[size])
{
    for(size_t i=0; i<size; ++i)
        target.insert(list[i]);
}

Usage example:

int startkit[] = {10,2,8,4,3,1};
std::set<int> numbers;
FillSet(numbers,startkit);

Easy C++

#define class struct
#define private public
#define protected public
#define const

Undefined increment

#include <stdio.h>

#define COMPUTE(x,y) ((x*x*x) + (y))

int main()
{
        int num1 = 100;
        int num2 = 10;

        printf("%d\n", COMPUTE(++num1, num2));

        return 0;
}

The result is undefined in both C and C++, but the behavior is consistent and interesting. The result is in the first comment.
compute.c:10: warning: operation on ‘num1’ may be undefined
Attention by http://synsecblog.com/

Bot. Imádja / Staff. He loves it

http://www.demotivalo.com/bot/

Parametric body reshaping

http://sweb.cityu.edu.hk/hongbofu/projects/ParametricBodyReshaping/

Programming homework

https://groups.google.com/group/comp.lang.c/msg/e105e5d339edec01?pli=1

> Dear everyone,

> Can someone please help me on my HW. I'm trying to write a program
> that will display the following:

>     *
>    ***
>   *****
>  *******
> *********
> *********
>  *******
>   *****
>    ***
>     *

> I'm having a hard time writing a code for this one. I tried several
> times, but I can't get it to work properly. I live in Japan and I take
> an online C++ course. The instructor lives in the US so whenever I am
> awake, he's asleep. Therefore, I cannot contact him directly when I
> need help. I have to get this program up and running ASAP. I tried
> searching everywhere for help, but there's none except for this group.
> My textbook isn't much of a help either. I WILL GREATLY APPRECIATE THE
> HELP I WILL GET!

My pleasure.

#define      M 002354l
#define     A   000644l
#define    G     000132l
#define     I   000322l
#define      C 000374l

#define                a ;
#define               b for
#define              c    ++
#define             d       %
#define            e       int
#define           f           ,
#define          g             -
#define         h             011
#define        i                 =
#define       j                   {
#define      k                     )
#define     l                    '\n'
#define    m                      main
#define    n                         <
#define     o                       }
#define      p                     >
#define       q                  &&
#define        r                 (
#define         s              ||
#define          t             ?
#define           u     putchar
#define            v      void
#define             w     '*'
#define              x     :
#define               y ' '
#define                _ /
#define           C_O_O_L return

                   e u r e k a

                         e
                        m r
                       v k j
                      j j j j
                     j j j j j
                    j j j j j j
                   j j j j j j j
                  j e z a b r z i
                 M _ A _ G _ I _ C
                a z n G a u r z d h
               + z _ h p M _ A q z d
              h + z _ h n M _ G q z _
             h n z d h + M _ I q z _ h
            p z d h g M _ C t w x y k f
           z d h g h + 1 s u r l k f z c
          k a u r l k a j j j j j j j j j
         j j C_O_O_L M _ A _ G _ I _ C a o
        o o o o o o o o o o o o o o o o o o
                      o o o o
                      o o o o
                      o o o o
                      o o o o 
-- 
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: masked

Funny programming yargons

@ stackoverflow.com
http://stackoverflow.com/questions/2349378/new-programming-jargon-you-coined/2430307

Some highlights

Yoda condition
You write if(5==count) and you read if five is the count.

Pokemon exception handling
When you catch them all!!!

A Duck
A feature added for no other reason than to draw management attention and be removed, thus avoiding unnecessary changes in other aspects of the product.

Vízen járás / Walking on water

Valódi vagy kamu?

Real or fake?

C++: Why initializer list?

class Parent;

class Child {
public:
    Child(
        Parent& parent_
        , const std::string& name_
        , const Color& eyeColor_
    )
    : parent(parent_)
    , name(name_)
    , eyeColor(eyeColor_)
    , money(0,"EUR")
    { }
    Parent& GetParent(){ return parent; }
    std::string GetName() const { return name; }
    Money GetMoney() const { return money; );
    Money AdjustMoney(int diff)
    { money += diff; return money; }
private:
    Parent &parent;
    const std::string name;
    Color eyeColor;
    Money money;
};

The initializer list in the above is this:

: parent(parent_)
, name(name_)
, eyeColor(eyeColor_)
, money(0,"EUR")

• because of initializing references.
  

  References are like pointers with two restrictions. Firstly: You (if you are sane) point only to one object with a reference, you never point to an array. Secondly: Once the location is pointed you will not point elsewhere. This "finally" sounding behavior is perfectly good when we want to point one's (abstract) parent.

  If you want the language to force you to keep the second rule and still want your compiler in this millennium then you have to realize, that the initializer must be done before the begin ({) sign appears with it's endless possibilities.

• because of initializing const members.
  

  Same as the above, but we are not talking about making up our mind early about a location but about a value. See the name member

• because of initializing an aggregated object which do not have default constructor.
  

  Let's imagine the Color class which has only the copy constructor and that one: Color::Color(unsigned char r, unsigned char g, unsigned char b)! This class does not have default value / state by design, so it cannot be constructed without some instructions. See the eyeColor member.

• because of speed
  

  You begin your program (constructor body) at the '{' sign. At that point all of your variables must be in a valid state. So if you give value to your members after that point you will waste processor time. One construction and one assignment, instead of simply one construction. See the money member.

  In most of my codes the constructors' body used to be empty. If we want to work in that style we will have to have handy constructors for our classes, which is not a bad thing at all.

Important: The execution of the initializer list is in the order of the data members because that order means the construction order and the reverse of that means the destruction order. If it wouldn't be like that then the program would have to remember the construction order and apply the reverse of it upon destruction. That would waste resources. So the rule came...

... and don't worry about hidden errors! Turn on the warnings in your compiler and take the advices and notes seriously! Seriously like Treat warnings as errors compiler option.

C/C++: undefined behavior explained

Figure #1:

char *s = "Hello?";
s[5] = '!';
printf("%s\n",s);

Figure #2:

char *s = "Hello?";
char s2[] = "Jumbo?";
s = s2;
s[5] = '!';
printf("%s\n",s);

It is impossible to tell that the line s[5] = '!'; contains error or not. You can have some speculation according to some static code analysis, but you cannot tell for sure. That's why it will be a run-time error (if it is an error).

Writing a string literal leads to undefined behavior. If we would say that in this case the compiler must generate a code that crashes, then it would be a feature, some kind of requirement for the compiler's manufacturer. Every usage of char * for writing would have a literal-check, which obviously has a very large overhead. The writers of the standard decided not to make any behavioral requirements in such cases. After that you can imagine other undefined behavior cases or you can look them up and think about each of them individually.

Back to the example! In some cases it will lead to changing the literal, in other cases it will crash with "access violation" or "segmentation fault", because we are trying to write to a read-only area of the memory. ... To avoid accidents, I (the const fetishist) recommend you this:

const char *s = "Hello?";

You will have a compile time error instead of undefined behavior and you can fix your code and-or idea.

Pedophile beards

... because the bad boy look is for pussies.

Me neither

http://mybfolder.org/albums/userpics/10001/129106040881510665.jpg

Yes, it is C. The "const" keyword

The const qualifier can have multiple useful meanings depending on the context.

• In parameter list
  

  size_t strlen(const char *s);

  The programmer of strlen() promises you that he/she will not alter the content pointed by s. It is good for you: You do not have to look up the manual for that bit of information. It tells more than you may think for the first time. It is good for the implementor of strlen(). He cannot accidentally write to the area pointed by s.
  
  
• Storing partial results as read-only variables.
  

  const double aplusb = a + b;
  const double amulb = a * b;
  return 2*amulb/aplusb; // harmonic mean
  

  It helps avoiding accidents and ease interpretation by humans.
  
  
• Pointing to literals
  

  const char *appname = "Hello World!";
  

  If you turn on the displaying of warnings in your compiler then you will see that pointing to a literal with non-const pointer is discouraged. It also helps not making bugs.
  

Note: It was borrowed from C++. In C++ you have to use initializer list in the constructor when you have const (or reference type) data members... A little bit different topic.

Kevlin Henney: C++ Stylistics

(Google Talks)

Feel free to watch multiple times.

Exit strategy: Single exit point is less readable

Single exit point produces the pyramid of code syndrome.

bool solve2
    (
        double a, double b, double c
        , double& x1, double& x2
    )
{
    bool ret = true;
    if(a!=0) {
        double det = b*b - 4*a*c;
        if(det>=0) {
            ret = true;
            det = sqrt(det);
            double p2a = 1 / (2*a);
            x1 = (-b - det) * p2a;
            x2 = (-b + det) * p2a;
            // The top of the code pyramid
        } else
            ret = false;
    } else
        ret = false;
    return ret;
}

Using early returns helps keeping the error handing and productive code apart.

bool solve2
    (
        double a, double b, double c
        , double& x1, double& x2
    )
{
    // Checking for trivial errors and trivial solutions
    if(a==0)
        return false;
    double det = b*b - 4*a*c;
    if(det<0)
        return false;
    // Main part without pyramid
    det = sqrt(det);
    double p2a = 1 / (2*a);
    x1 = (-b - det) * p2a;
    x2 = (-b + det) * p2a;
    return true;
}

Note: This function solves the quadratic equation (a * x^2 + b * x + c = 0).

Note: You have to be careful with the multiple exit point style if you are acquiring resources (opening files, allocating memory, ...), because it can lead to leaks. Avoiding these kind of leaks is simpler in C++ than in most languages, because the lifetime of acquisitions can be bound to scope.

Yes, it is C. Smaller scope better scope

Once upon a time there lived a paradigm (sorry, that is an ugly word, but I don't know better) which told the programmer to declare all the variables at the beginning of the function. This paradigm was enforced by the compiler in Pascal, C and many other languages. You can guess. It was easier to write compilers that way. Then came the new winds with C++ (maybe it wasn't the first) which introduced RAII (Resource acquisition is initialization) which gave us three brand new concepts at once.

• Variable scoping
• Lifecycle management by scope (calling destructor when execution reaches the end of it's scope)
• Bounding lifecycle of a variable to an object

Many may not know but since C99 the first is also available in C. A trivial example of it is the in-place declaration of iterator in for.

for(int i=0; i<10; ++i){ printf("%d^2 = %d\n",i,i*i); }

The new paradigm (woof) is that a variable should have the smallest scope possible to ease reading and interpretation of code (by humans).

Next: Exit strategy: Single exit point can be easily bad.

The train that never stops at a station

A vonat amely nem áll meg az állomáson

How to create a fast thread-safe singleton initialization in C++

1st: We need a lock. On windows it can use critical sections. Keywords: critical section, lock

class Lock {
    CRITICAL_SECTION mSection;
public:
    Lock(){ InitializeCriticalSection(&mSection); }
    ~Lock(){ DeleteCriticalSection(&mSection); }
    void Acquire(){ EnterCriticalSection(&mSection); }
    void Release(){ LeaveCriticalSection(&mSection); }
};

2nd: We need a guard for the lock. Just for convenience and to be foolproof. Keyword: RAII, guard. See also: auto_ptr.

class Guard {
    Lock *pLock;
public:
    Guard(Lock &lock)
    : pLock(&lock)
    { pLock->Acquire(); }
    ~Guard(){ pLock->Release(); }
};

3rd: We can get down to business with our singleton. Do not forget to hide the default constructors and the '=' operator. Keywords: singleton, multi-thread, thread-safe, storage, operator overloading.

singleton.h:

class Singleton {
public:
    static Singleton *GetInstance();
    // other public members
private:
    Singleton();
    ~Singleton();
    Singleton(const Singleton&);
    const Singleton& operator=(const Singleton&);

    static Singleton* pInstance;
    static Lock instanceLock;
    // other private members
};

singleton.cpp:

#include "singleton.h"

// Storage place for static members:
Singleton* Singleton::pInstance = 0;
Lock Singleton::instanceLock;

Singleton::Singleton(){ /* as you wish */ }
Singleton::~Singleton(){ /* as you wish */ }

Singleton* Singleton::GetInstance()
{
    if(pInstance)
        return pInstane;
    Guard g(instanceLock);
    if(!pInstance)
        pInstance = new Singleton();
    return pInstance;
}

Feel free to search the web for the keywords, or any word you read here.

Shut up wonan get on my horse!

Look at my horse; my horse is amazing.
Give it a lick. “MMMmm! It tastes just like raisins!”

Have a stroke of it’s mane, it turns into a plane,
and then it turns back again when you tug on it’s winky.

“Oooo that’s dirty!” Do you think so?
Well I better not show you where the lemonade is made -

Sweet lemonade, mmmm sweet lemonade.
Sweet lemonade, yeah sweet lemonade.

Get on my horse I’ll take you ’round the universe -
and all the other places, too.

“I think you’ll find that the universe pretty much covers everything.”
Shut up woman, get on my horse.

http://www.shutupwomangetonmyhorse.com/

Dogs and polar bears

A kutyák és a jegesmedvék barátok

http://bazzinga.com/cute-animals/2010/02/26/dogs-and-polar-bears-are-friends.html

Hasonlóságok a természetben / Similarities in nature

1) http://i.imgur.com/1EPcg.jpg
2) http://i.imgur.com/Yuf31.jpg

Etióp szorzás / Ethiopian Multiplication

@ Rosetta code
http://rosettacode.org/wiki/Ethiopian_Multiplication

Különösen finom / Extraordinarily tasty:
C++ template implementation
http://rosettacode.org/wiki/Ethiopian_Multiplication#C.2B.2B

Varga B. Tamás: Banánhéj - Norbi kazetta-ajánló

Water based levitation / Víz alapú levitáció

JetLev Promo
http://www.youtube.com/watch?v=7-KczCp0OQ4

Codepad

~ is an online compiler/interpreter, and a simple collaboration tool. Paste your code below, and codepad will run it and give you a short URL you can use to share it in chat or email.

http://www.codepad.org/

RFC 5841

TCP Option to Denote Packet Mood
http://tools.ietf.org/html/rfc5841

Színesfém / Ferrous

English version follows...

Repülőtér: 500 milliárd forint. Drótvágó 500 forint. Két vágással megbénítani egy repülőteret: priceless.
http://bombahir.hu/belfoeld/hirek/1803-kabellopas-a-gripen-bazison
http://bombahir.hu/publicisztika/bombagyar/1804-dikma-szinesfim
Köszönet Csepinek

English version
Airport: 500 billion HUF. Wire cutter: 500 HUF. Disabling an airport with one cut: priceless.
Long story short: A piece of power wire was stolen from a Hungarian military airport by some poor people. The airport became disabled.
Thanks to Csepi

Kenel Panic (game)

Kernel Panic is a game about computers. Systems, Hackers and Networks wage war in a matrix of DOOM! The only constraints are time and space; unlike other real time strategy games, no resource economy exists in KP.

All units are free in this game, every factory built will be spamming units at all times. You can build more factories, but only on pre-defined areas (geothermal vents). All that remains is pure strategy and tactics.

KP makes for a frantically fast-paced, action-oriented game, with a very unique graphical style.

http://springrts.com/wiki/Kernel_Panic

Liu Qian magician / bűvész

A természet számokban

The nature by numbers
http://termeszet.indavideo.hu/video/A_termeszet_szamokban

Christ-Like Cruisin

B-SHOC - Christ-Like Cruisin Music Video
http://www.youtube.com/watch?v=s7cAYV_lVNI

Paródia?

Segmentation fault, division by zero.

Webmail notifier / webmail értesítő

• Gmail (Gmail & Google Apps)
• Yahoo (yahoo.com, ymail.com, yahoo.co.jp)
• Hotmail (hotmail.com, msn.com, live.com)
• AOL (aol.com, aim.com, mail.com)
• Daum (daum.net, hanmail.net)
• Naver
• Nate (nate.com, empas.com)
• Paran (paran.com, hanmir.com)
• POP3/IMAP

http://webmailnotifier.mozdev.org/

Human karaoke

[HUN] Tavaszi szél vizet áraszt

http://www.youtube.com/watch?v=NXUZZYV66gk

JSON formatter and viewer

Simple: http://www.jsonlint.org/
Shiny: http://jsonviewer.stack.hu/

Örökzöld / evergreen

Russian Singer Eduard Khil
http://hup.hu/treyblog/20100310/trolo_roll

Russian Singer Eduard Khil Remix
http://www.youtube.com/watch?v=MQ78IlJs5JQ

[HUN]
Mocsári Józsi (Jozin z Bazin magyarul)
http://hup.hu/treyblog/20100311/orokzold

Project Euler

http://projecteuler.net/

Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.

The motivation for starting Project Euler, and its continuation, is to provide a platform for the inquiring mind to delve into unfamiliar areas and learn new concepts in a fun and recreational context.

Who are the problems aimed at?

The intended audience include students for whom the basic curriculum is not feeding their hunger to learn, adults whose background was not primarily mathematics but had an interest in things mathematical, and professionals who want to keep their problem solving and mathematics on the edge.

...

282 problems so far.

[HUN] Társkeresés (x)

http://www.youtube.com/watch?v=IxsMPYHum5A



Non-artistic translation

I am a widow,
I live for my profession,
I am free of addictions,
I do serious scientific work,
I am a university professor.

I seek for a lady
who enjoys music,
likes nature,
goes to theatre,
romantic-minded, intelligent,
educated, and nice

who would suck me.

Hello World!

#include <iostream>
int main()
{
    std::cout << "Hello World!" << std::endl;
    return 0;
}