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  • In the following implementation of static_strlen, why are the & and parentheses around str necessary

    - by Ben
    If I change the type to const char str[Len], I get the following error: error: no matching function for call to ‘static_strlen(const char [5])’ Am I correct that static_strlen expects an array of const char references? My understanding is that arrays are passed as pointers anyway, so what need is there for the elements to be references? Or is that interpretation completely off-the-mark? #include <iostream> template <size_t Len> size_t static_strlen(const char (&str)[Len]) { return Len - 1; } int main() { std::cout << static_strlen("oyez") << std::endl; return 0; }

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  • Differences between matrix implementation in C

    - by tempy
    I created two 2D arrays (matrix) in C in two different ways. I don't understand the difference between the way they're represented in the memory, and the reason why I can't refer to them in the same way: scanf("%d", &intMatrix1[i][j]); //can't refer as &intMatrix1[(i * lines)+j]) scanf("%d", &intMatrix2[(i * lines)+j]); //can't refer as &intMatrix2[i][j]) What is the difference between the ways these two arrays are implemented and why do I have to refer to them differently? How do I refer to an element in each of the arrays in the same way (?????? in my printMatrix function)? int main() { int **intMatrix1; int *intMatrix2; int i, j, lines, columns; lines = 3; columns = 2; /************************* intMatrix1 ****************************/ intMatrix1 = (int **)malloc(lines * sizeof(int *)); for (i = 0; i < lines; ++i) intMatrix1[i] = (int *)malloc(columns * sizeof(int)); for (i = 0; i < lines; ++i) { for (j = 0; j < columns; ++j) { printf("Type a number for intMatrix1[%d][%d]\t", i, j); scanf("%d", &intMatrix1[i][j]); } } /************************* intMatrix2 ****************************/ intMatrix2 = (int *)malloc(lines * columns * sizeof(int)); for (i = 0; i < lines; ++i) { for (j = 0; j < columns; ++j) { printf("Type a number for intMatrix2[%d][%d]\t", i, j); scanf("%d", &intMatrix2[(i * lines)+j]); } } /************** printing intMatrix1 & intMatrix2 ****************/ printf("intMatrix1:\n\n"); printMatrix(*intMatrix1, lines, columns); printf("intMatrix2:\n\n"); printMatrix(intMatrix2, lines, columns); } /************************* printMatrix ****************************/ void printMatrix(int *ptArray, int h, int w) { int i, j; printf("Printing matrix...\n\n\n"); for (i = 0; i < h; ++i) for (j = 0; j < w; ++j) printf("array[%d][%d] ==============> %d\n, i, j, ??????); }

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  • Event feed implementation - will it scale?

    - by SlappyTheFish
    Situation: I am currently designing a feed system for a social website whereby each user has a feed of their friends' activities. I have two possible methods how to generate the feeds and I would like to ask which is best in terms of ability to scale. Events from all users are collected in one central database table, event_log. Users are paired as friends in the table friends. The RDBMS we are using is MySQL. Standard method: When a user requests their feed page, the system generates the feed by inner joining event_log with friends. The result is then cached and set to timeout after 5 minutes. Scaling is achieved by varying this timeout. Hypothesised method: A task runs in the background and for each new, unprocessed item in event_log, it creates entries in the database table user_feed pairing that event with all of the users who are friends with the user who initiated the event. One table row pairs one event with one user. The problems with the standard method are well known – what if a lot of people's caches expire at the same time? The solution also does not scale well – the brief is for feeds to update as close to real-time as possible The hypothesised solution in my eyes seems much better; all processing is done offline so no user waits for a page to generate and there are no joins so database tables can be sharded across physical machines. However, if a user has 100,000 friends and creates 20 events in one session, then that results in inserting 2,000,000 rows into the database. Question: The question boils down to two points: Is this worst-case scenario mentioned above problematic, i.e. does table size have an impact on MySQL performance and are there any issues with this mass inserting of data for each event? Is there anything else I have missed?

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  • Best pageable table implementation in GWT

    - by Steve Buikhuizen
    I need to add a paging, sortable table to my GWT application. I see lots of these out there so I'm looking for your experience to save me time by choosing the best one. So far I'm looking at... http://code.google.com/p/gwt-advanced-table/ http://code.google.com/p/google-web-toolkit-incubator/wiki/PagingScrollTableOld I like the second one best. Any stories to tell?

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  • MySQL Hashing Function Implementation

    - by Jonas Stevens
    I know that php has md5(), sha1(), and the hash() functions, but I want to create a hash using the MySQL PASSWORD() function. So far, the only way I can think of is to just query the server, but I want a function (preferably in php or Perl) that will do the same thing without querying MySQL at all. For example: MySQL hash - 464bb2cb3cf18b66 MySQL5 hash - *01D01F5CA7CA8BA771E03F4AC55EC73C11EFA229 Thanks!

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  • Program hangs when calling parseFrom for java implementation of protobuf

    - by cornerback84
    I have a message (say its called OuterMessage) message OuterMessage { optional int64 id = 1; optional InnerMessage inner = 2; } and an inner message message InnerMessage { optional string type = 1; optioanl int64 id = 2; } Now when I call parseFrom on OuterMessage like OuterMessage.parseFrom(buffer) the method never returns and nor does it throw any exception. But if I do InnerMessage.parseFrom(buffer) it returns an empty InnerMessage instance. I am serializing the message using protobuf-net. Any idea what might be causing the issue?

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  • I have a generic implementation of PHP mcrypt module and its not decrypting

    - by Ken Mitchner
    class Crypt_Data { protected $_mcrypt=null; protected $_iv=null; protected $_key=null; public function __construct() { $this->_mcrypt = mcrypt_module_open('rijndael_256', '', 'cbc', ''); $key_size = mcrypt_enc_get_key_size($this->_mcrypt); for($i=0;$i<$key_size;$i++) $test_key .= "0"; $this->_iv = $test_key; $this->_key = $test_key; mcrypt_generic_init($this->_mcrypt,$this->_key,$this->_iv); } public function dataEncrypt($data) { return base64_encode(mcrypt_generic($this->_mcrypt, $data)); } public function dataDecrypt($data) { return mdecrypt_generic($this->_mcrypt, base64_decode($data)); } } $crypt = new Crypt_Data(); $string = "encrypt me"; $encrypted = $crypt->dataEncrypt($string); echo $encrypted."<BR>"; $decrypted = $crypt->dataDecrypt($encrypted); echo $decrypted."<BR>"; output: JJKfKxZckkqwfZ5QWeyVR+3PkMQAsP0Gr1hWaygV20I= qÌÌi_ÖZí(®`iÜ¥wÝÿ ô0€Í6Ÿhf[%ër No idea why this isn't working, everything seems to be fine on my end.. i tried decrypting it with mcrypt_cbc(); and it decrypted it properly.. so it has something to do with my mdecrypt_generic.. any ideas?

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  • Cross-Browser jQuery text-zoom implementation

    - by JMC Creative
    I've got some code to increase/decrease font size. This is giving me a headache because each browser seems to implement the $.css('font-size') differently (see jquery bug). The part that's really killing me, though, is that Firefox is scaling up okay, but when I use the scale down function below, it scales up. Webkit & IE are both working as expected. Any ideas on that? I put this in a fiddle here: http://jsfiddle.net/srQ3P/1/ where you can see it working as expected, and you can see it broken in firefox at the project page: http://cumberlandme.info/residents MAJOR EDIT Sorry, the issue is not the code, it's firefox buggy behavior. After I zoom in or out with the browser controls (ctrl + plus or ctrol + minus) the js goes haywire. This doesn't happen in other browsers. This is the real issue. Any advice on that

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  • Facebook implementation in android

    - by Sanat Pandey
    I am implementing Facebook in my app through FbRocket jar, but it gives some error as ClassNotFound, but I don't know why bcoz i have alredy added that jar in libraries........ Please help me out. 05-09 19:04:28.933: ERROR/AndroidRuntime(759): FATAL EXCEPTION: main 05-09 19:04:28.933: ERROR/AndroidRuntime(759): java.lang.NoClassDefFoundError: net.xeomax.FBRocket.FBRocket 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at org.shopzilla.android.moretab.SettingActivity.shareFacebook(SettingActivity.java:73) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at org.shopzilla.android.moretab.SettingActivity$2.onClick(SettingActivity.java:63) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at android.view.View.performClick(View.java:2485) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at android.view.View$PerformClick.run(View.java:9080) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at android.os.Handler.handleCallback(Handler.java:587) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at android.os.Handler.dispatchMessage(Handler.java:92) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at android.os.Looper.loop(Looper.java:123) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at android.app.ActivityThread.main(ActivityThread.java:3683) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at java.lang.reflect.Method.invokeNative(Native Method) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at java.lang.reflect.Method.invoke(Method.java:507) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 05-09 19:04:28.933: ERROR/AndroidRuntime(759): at dalvik.system.NativeStart.main(Native Method) Code: package org.shopzilla.android.moretab; import java.util.List; import net.xeomax.FBRocket.FBRocket; import net.xeomax.FBRocket.Facebook; import net.xeomax.FBRocket.ServerErrorException; import org.apache.http.NameValuePair; import org.apache.http.client.HttpClient; import org.shopzilla.android.common.R; import org.shopzilla.android.facebook.FacebookActivity; import org.shopzilla.android.facebook.FacebookWebOAuthActivity; import org.shopzilla.android.twitter.TwitterActivity; import org.shopzilla.android.twitter.TwitterWebOAuthActivity; import twitter4j.http.RequestToken; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.TextView; public class SettingActivity extends Activity{ String bytesSent; HttpClient httpclient; int count1; // List with parameters and their values List<NameValuePair> nameValuePairs; TextView mText; Button btn_facebook; Button btn_twitter; FBRocket fbRocket; RequestToken rToken; String oauthVerifier; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.more_setting); Button btn_twitter = (Button)findViewById(R.id.btn_more_setting_twitter); Button btn_facebook = (Button)findViewById(R.id.btn_More_setting_facebook); btn_twitter.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { // TODO Auto-generated method stub Intent intent = new Intent(SettingActivity.this,TwitterActivity.class); startActivity(intent); //displayTwitterAuthorization(); } }); btn_facebook.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { // TODO Auto-generated method stub /*Intent intent = new Intent(SettingActivity.this,FacebookActivity.class); startActivity(intent);*/ shareFacebook(); //displayFacebookAuthorization(); //shareFacebook(); } }); } public void shareFacebook() { fbRocket = new FBRocket(SettingActivity.this, "ShopZilla", "172619129456913"); if (fbRocket.existsSavedFacebook()) { fbRocket.loadFacebook(); } else { fbRocket.login(R.layout.facebook); } } public void onLoginFail() { fbRocket.displayToast("Login failed!"); fbRocket.login(R.layout.facebook); } public void onLoginSuccess(Facebook facebook) { // TODO Auto-generated method stub fbRocket.displayToast("Login success!"); try { facebook.setStatus("This is your status"); fbRocket.displayDialog("Status Posted Successfully!! " + facebook.getStatus()); } catch (ServerErrorException e) { if (e.notLoggedIn()) { fbRocket.login(R.layout.facebook); } else { System.out.println(e); } } } }

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  • DRYing out implementation of ICloneable in several classes

    - by Sarah Vessels
    I have several different classes that I want to be cloneable: GenericRow, GenericRows, ParticularRow, and ParticularRows. There is the following class hierarchy: GenericRow is the parent of ParticularRow, and GenericRows is the parent of ParticularRows. Each class implements ICloneable because I want to be able to create deep copies of instances of each. I find myself writing the exact same code for Clone() in each class: object ICloneable.Clone() { object clone; using (var stream = new MemoryStream()) { var formatter = new BinaryFormatter(); // Serialize this object formatter.Serialize(stream, this); stream.Position = 0; // Deserialize to another object clone = formatter.Deserialize(stream); } return clone; } I then provide a convenience wrapper method, for example in GenericRows: public GenericRows Clone() { return (GenericRows)((ICloneable)this).Clone(); } I am fine with the convenience wrapper methods looking about the same in each class because it's very little code and it does differ from class to class by return type, cast, etc. However, ICloneable.Clone() is identical in all four classes. Can I abstract this somehow so it is only defined in one place? My concern was that if I made some utility class/object extension method, it would not correctly make a deep copy of the particular instance I want copied. Is this a good idea anyway?

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  • ViewPager and Fragment Pager adapter implementation

    - by Rohit Deshmukh
    So I am trying to implement sliding views/fragments using viewpager and fragment pager adapter. convert_home is my main xml file that has android.support.v4.view.PagerTitleStrip and temperature.xml and velocity.xml are my two other views. I have no clue where I am going wrong. package app.converto; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager; import android.view.LayoutInflater; import android.view.Menu; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; public class ConverTo extends FragmentActivity { SectionsPagerAdapter mSectionsPagerAdapter; ViewPager mViewPager; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager()); mViewPager.setAdapter(mSectionsPagerAdapter); setContentView(R.layout.converto_home); mViewPager = (ViewPager) findViewById(R.id.pager); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.converto_home, menu); return true; } public class SectionsPagerAdapter extends FragmentPagerAdapter { public SectionsPagerAdapter(FragmentManager fm) { super(fm); } @Override public Fragment getItem(int i) { switch(i){ case 0: Fragment1 fragment = new Fragment1(); return fragment; case 1: Fragment2 fragment2 = new Fragment2(); return fragment2; } defaultFragment fragment3 = new defaultFragment(); return fragment3; } @Override public int getCount() { return 2; } // // @Override // public CharSequence getPageTitle(int position) { // switch (position) { // case 0: return getString(R.string.velocity); // case 1: return getString(R.string.temperature); // case 2: return getString(R.string.distance); // } // return null; // } } public static class Fragment1 extends Fragment{ public Fragment1(){ } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { //return inflater.inflate(R.layout.temperature, container, false); View view = inflater.inflate(R.layout.temperature, container, false); TextView textView = (TextView) view.findViewById(R.id.sample); textView.setText(getArguments().getString("title")); return view; } } public static class Fragment2 extends Fragment{ public Fragment2(){ } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { //return inflater.inflate(R.layout.velocity, container, false); View view = inflater.inflate(R.layout.temperature, container, false); TextView textView = (TextView) view.findViewById(R.id.sample); textView.setText(getArguments().getString("title")); return view; } } public static class defaultFragment extends Fragment{ public defaultFragment(){ }//end constructor @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // return inflater.inflate(R.layout.temperature, container, false); View view = inflater.inflate(R.layout.temperature, container, false); TextView textView = (TextView) view.findViewById(R.id.sample); textView.setText(getArguments().getString("title")); return view; }//end oncreate }//end default fragment }

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  • Ajax with Jsf 1.1 implementation

    - by Rohan Ved
    I am using JSF1.1 in that, have this code_ <%@ taglib uri="http://java.sun.com/jsf/html" prefix="h"%> <%@ taglib uri="http://java.sun.com/jsf/core" prefix="f"%> <%@ taglib uri="http://www.azureworlds.org" prefix="azure"%> <%@ taglib uri="http://myfaces.apache.org/tomahawk" prefix="x"%> <%@ taglib uri="http://www.asifqamar.com/jsf/asif" prefix="a"%> ... <x:selectOneMenu value="#{hotelBean.state}"> <f:selectItem itemLabel="Select One" itemValue="" /> <f:selectItem value="#{hotelBean.mapStates }" /> <x:ajax update="city" listener="#{hotelBean.handleCityChange}" /> </x:selectOneMenu> <h:outputText value="City* " /> <x:selectOneMenu id="city" value="#{hotelBean.city}"> <f:selectItem itemLabel="Select One" itemValue="" /> <f:selectItem value="#{hotelBean.mapCities }" /> </x:selectOneMenu> line x:ajax update="city" listener="#{hotelBean.handleCityChange}" is not working , i searched but got JSF1.1 not support for Ajax. then what can i do for this? and i have less knowledge of JS. Thanx

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  • Windows DD-esque implementation in Qt 5

    - by user1777667
    I'm trying to get into Qt and as a project I want to try and pull a binary image from a hard drive in Windows. This is what I have: QFile dsk("//./PhysicalDrive1"); dsk.open(QIODevice::ReadOnly); QByteArray readBytes = dsk.read(512); dsk.close(); QFile img("C:/out.bin"); img.open(QIODevice::WriteOnly); img.write(readBytes); img.close(); When I run it, it creates the file, but when I view it in a hex editor, it says: ëR.NTFS ..........ø..?.ÿ.€.......€.€.ÿç......UT..............ö.......ì§á.Íá.`....ú3ÀŽÐ¼.|ûhÀ...hf.ˈ...f.>..NTFSu.´A»ªUÍ.r..ûUªu.÷Á..u.éÝ..ƒì.h..´HŠ...‹ô..Í.ŸƒÄ.žX.rá;...uÛ£..Á.....Z3Û¹. +Èfÿ.......ŽÂÿ...èK.+Èwï¸.»Í.f#Àu-f.ûTCPAu$.ù..r..h.».hp..h..fSfSfU...h¸.fa..Í.3À¿(.¹Ø.üóªé_...f`..f¡..f.....fh....fP.Sh..h..´BŠ.....‹ôÍ.fY[ZfYfY..‚..fÿ.......ŽÂÿ...u¼..faàø.è.. û.è..ôëý´.‹ð¬<.t.´.»..Í.ëòÃ..A disk read error occurred...BOOTMGR is missing...BOOTMGR is compressed...Press Ctrl+Alt+Del to restart...Œ©¾Ö..Uª Is there a better way of doing this? I tried running it as admin, but still no dice. Any help would be much appreciated. Update: I changed the code a bit. Now if I specify a dd images as the input it writes the image perfectly, but when I try to use a disk as the input it only writes 0x00. QTextStream(stdout) << "Start\n"; QFile dsk("//./d:"); //QFile dsk("//./PhysicalDrive1"); //QFile dsk("//?/Device/Harddisk1/Partition0"); //QFile dsk("//./Volume{e988ffc3-3512-11e3-99d8-806e6f6e6963}"); //QFile dsk("//./Volume{04bbc7e2-a450-11e3-a9d9-902b34d5484f}"); //QFile dsk("C:/out_2.bin"); if (!dsk.open(QIODevice::ReadOnly)) qDebug() << "Failed to open:" << dsk.errorString(); qDebug() << "Size:" << dsk.size() << "\n"; // Blank out image file QFile img(dst); img.open(QIODevice::WriteOnly); img.write(0); img.close(); // Read and write operations while (!dsk.atEnd()) { QByteArray readBytes = dsk.readLine(); qDebug() << "Reading: " << readBytes.size() << "\n"; QFile img(dst); if (!img.open(QIODevice::Append)) qDebug() << "Failed to open:" << img.errorString(); img.write(readBytes); } QTextStream(stdout) << "End\n"; I guess the real problem I'm having is how to open a volume with QFile in Windows. I tried a few variants, but to no avail.

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  • Is this implementation truely tail-recursive?

    - by CFP
    Hello everyone! I've come up with the following code to compute in a tail-recursive way the result of an expression such as 3 4 * 1 + cos 8 * (aka 8*cos(1+(3*4))) The code is in OCaml. I'm using a list refto emulate a stack. type token = Num of float | Fun of (float->float) | Op of (float->float->float);; let pop l = let top = (List.hd !l) in l := List.tl (!l); top;; let push x l = l := (x::!l);; let empty l = (l = []);; let pile = ref [];; let eval data = let stack = ref data in let rec _eval cont = match (pop stack) with | Num(n) -> cont n; | Fun(f) -> _eval (fun x -> cont (f x)); | Op(op) -> _eval (fun x -> cont (op x (_eval (fun y->y)))); in _eval (fun x->x) ;; eval [Fun(fun x -> x**2.); Op(fun x y -> x+.y); Num(1.); Num(3.)];; I've used continuations to ensure tail-recursion, but since my stack implements some sort of a tree, and therefore provides quite a bad interface to what should be handled as a disjoint union type, the call to my function to evaluate the left branch with an identity continuation somehow irks a little. Yet it's working perfectly, but I have the feeling than in calling the _eval (fun y->y) bit, there must be something wrong happening, since it doesn't seem that this call can replace the previous one in the stack structure... Am I misunderstanding something here? I mean, I understand that with only the first call to _eval there wouldn't be any problem optimizing the calls, but here it seems to me that evaluation the _eval (fun y->y) will require to be stacked up, and therefore will fill the stack, possibly leading to an overflow... Thanks!

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  • internal implementation of database Queries

    - by harigm
    In my experience I have used many queries like select, order by, where clause etc.. in mysql, sql-server, oracle etc For a moment i have thought, 1)how is this internally written to implement the above queries 2) which language do they use? 3) is that programming language? if yes which language? 4)what kind of environment required to implement this kind of complex database

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  • doubt in sizeof implementation

    - by aks
    Below is the program to find the size of a structure without using sizeof operator: struct MyStruct { int i; int j; }; int main() { struct MyStruct *p=0; int size = ((char*)(p+1))-((char*)p); printf("\nSIZE : [%d]\nSIZE : [%d]\n", size); return 0; } My doubt is: Why is typecasting to char * required? If I don't use the char* pointer, the output is 1 - WHY?

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  • Drag and drop an image from desktop to a web text editor (implementation in javascript)

    - by fatmatto
    I tried to write reasonably short title but i failed i guess.. Hi everybody here's what i'm trying to do: I want to implement a web text editor able to recognize when the user drag a image file over it's editing surface and it automa(gically) starts the upload and insert the image near the cursor position. In other words i don't want the user to do the usual "insert-image-browse-ok". Atm i am not very good at javascript ... i know JQuery but i have not a clear idea about how to implement this... i don't know if there's an event handler able to help me in this situation... if not then there should be i think or web apps would miss some kind of interactivity. I've heard miracles about HTML5 could it help me? I've seen such things in Google Wave but that surface doesn't seem to be a form field... google lab's black magic i guess.... Thank you in advance.

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  • Implementation of APIs on diferent platforms

    - by b-gen-jack-o-neill
    OK, this is basicly just about any non-default OS API running on all different OS. But for my example let´s consider platform Windows, API SDL (Simple DirectMedia Layer). Actually this question came to my mind when I was reading about SDL. Originally, I thought that on Windows (and basicly any other OS) you must use OS API to make certain actions, like wrtiting to screen, creating window and so on, becouse that API knows what kernel calls and system subroutines calls it has to do. But when I read about SDL, I surprised me, becouse, you cannot make computer to do anything more than OS can, since you cannot acess HW directly, only thru OS API, from Console allocation to DirectX. So, my question actually is, how does this not-default-OS APIs work? Do they use (wrap) original system API (like MFC wraps win32 api)? Or, do they actually have direct acess to Windows kernel? Or is there any third, way in between? Thanks.

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  • What's the recommended implementation for hashing OLE Variants?

    - by Barry Kelly
    OLE Variants, as used by older versions of Visual Basic and pervasively in COM Automation, can store lots of different types: basic types like integers and floats, more complicated types like strings and arrays, and all the way up to IDispatch implementations and pointers in the form of ByRef variants. Variants are also weakly typed: they convert the value to another type without warning depending on which operator you apply and what the current types are of the values passed to the operator. For example, comparing two variants, one containing the integer 1 and another containing the string "1", for equality will return True. So assuming that I'm working with variants at the underlying data level (e.g. VARIANT in C++ or TVarData in Delphi - i.e. the big union of different possible values), how should I hash variants consistently so that they obey the right rules? Rules: Variants that hash unequally should compare as unequal, both in sorting and direct equality Variants that compare as equal for both sorting and direct equality should hash as equal It's OK if I have to use different sorting and direct comparison rules in order to make the hashing fit. The way I'm currently working is I'm normalizing the variants to strings (if they fit), and treating them as strings, otherwise I'm working with the variant data as if it was an opaque blob, and hashing and comparing its raw bytes. That has some limitations, of course: numbers 1..10 sort as [1, 10, 2, ... 9] etc. This is mildly annoying, but it is consistent and it is very little work. However, I do wonder if there is an accepted practice for this problem.

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  • GetIDsOfNames implementation

    - by fearlesscoder
    Hi all, I need to implement GetIDsOfNames in my C++ application and I have no idea how to do that. I understand that I should implement GetTypeInfo, GetTypeInfoCount for that. I found a code sample which uses LIBID, but I don't have LIBID, and I don't know where to get one. What I really need is a good explanation of IDispatch interface internals...

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