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• Unique ways to use the Null Coalescing operator

  - by Atomiton

  I know the standard way of using the Null coalescing operator in C# is to set default values. string nobody = null; string somebody = "Bob Saget"; string anybody = ""; anybody = nobody ?? "Mr. T"; // returns Mr. T anybody = somebody ?? "Mr. T"; // returns "Bob Saget" But what else can ?? be used for? It doesn't seem as useful as the ternary operator, apart from being more concise and easier to read than: nobody = null; anybody = nobody == null ? "Bob Saget" : nobody; // returns Bob Saget So given that fewer even know about null coalescing operator... Have you used ?? for something else? Is ?? necessary, or should you just use the ternary operator (that most are familiar with)

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• null pointers vs. Null Object Pattern

  - by GlenH7

  Attribution: This grew out of a related P.SE question My background is in C / C++, but I have worked a fair amount in Java and am currently coding C#. Because of my C background, checking passed and returned pointers is second-hand, but I acknowledge it biases my point of view. I recently saw mention of the Null Object Pattern where the idea is than an object is always returned. Normal case returns the expected, populated object and the error case returns empty object instead of a null pointer. The premise being that the calling function will always have some sort of object to access and therefore avoid null access memory violations. So what are the pros / cons of a null check versus using the Null Object Pattern? I can see cleaner calling code with the NOP, but I can also see where it would create hidden failures that don't otherwise get raised. I would rather have my application fail hard (aka an exception) while I'm developing it than have a silent mistake escape into the wild. Can't the Null Object Pattern have similar problems as not performing a null check? Many of the objects I have worked with hold objects or containers of their own. It seems like I would have to have a special case to guarantee all of the main object's containers had empty objects of their own. Seems like this could get ugly with multiple layers of nesting.

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• What do you think about ??= operator in C#?

  - by TN

  Do you think that C# will support something like ??= operator? Instead of this: if (list == null) list = new List<int>(); It might be possible to write: list ??= new List<int>(); Now, I could use (but it seems to me not well readable): list = list ?? new List<int>();

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• How do I fix a noisy input device (Internal Mic)? snd_hda_intel - debug included

  - by hazrpg

  As the title says, I'm having trouble with a very noisy audio input device - the internal mic or any plugged in mics. So far I've narrowed it down to an problem in ALSA since my debug info is showing a lot of "null" values. Can anyone help? Debug Info: http://www.alsa-project.org/db/?f=e0c6fb7e10624bf7691aa2b405cf0d3968e56c63 Exert from the debug: model : (null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null)

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• null coalescing operator for javascript?

  - by Daniel Schaffer

  I assumed this question has already been asked here, but I couldn't find any, so here it goes: Is there a null coalescing operator in Javascript? For example, in C#, I can do this: String someString = null; var whatIWant = someString ?? "Cookies!"; The best approximation I can figure out for Javascript is using the conditional operator: var someString = null; var whatIWant = someString ? someString : 'Cookies!'; Which is sorta icky IMHO. Can I do better?

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• Null Or Empty Coalescing

  - by Latest Microsoft Blogs

  In my last blog post, I wrote about the proper way to check for empty enumerations and proposed an IsNullOrEmpty method for collections which sparked a lot of discussion. This post covers a similar issue, but from a different angle. A very long time ago Read More......(read more)

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• Why friend overloaded operator is preferred to conversion operator in this case

  - by skydoor

  Hi I have a code like this, I think both the friend overloaded operator and conversion operator have the similar function. However, why does the friend overloaded operator is called in this case? What's the rules? Thanks so much! class A{ double i; public: A(int i):i(i) {} operator double () const { cout<<"conversion operator"<<endl;return i;} // a conversion operator friend bool operator>(int i, A a); // a friend funcion of operator > }; bool operator>(int i, A a ){ cout<<"Friend"<<endl; return i>a.i; } int main() { A aa(1); if (0 > aa){ return 1; } }

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• Shortcut "or-assignment" (|=) operator in Java

  - by Dr. Monkey

  I have a long set of comparisons to do in Java, and I'd like to know if one or more of them come out as true. The string of comparisons was long and difficult to read, so I broke it up for readability, and automatically went to use a shortcut operator |= rather than negativeValue = negativeValue || boolean. boolean negativeValue = false; negativeValue |= (defaultStock < 0); negativeValue |= (defaultWholesale < 0); negativeValue |= (defaultRetail < 0); negativeValue |= (defaultDelivery < 0); I expect negativeValue to be true if any of the default<something> values are negative. Is this valid? Will it do what I expect? I couldn't see it mentioned on Sun's site or stackoverflow, but Eclipse doesn't seem to have a problem with it and the code compiles and runs.

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• C# Operator Overloading post-fix increment

  - by Victor

  I'm coding a date class and am having trouble with the post-fix increment (the prefix increment seems fine). Here is the sample code: public class date { int year, month, day; public date(int d, int m, int y) { day = d; month = m; year = y; } static public date operator ++(date d) { return d.Next(d); } } The method "Next(date d)" takes a date and returns tomorrows date (I left it out for brevity). I'm to young in C# to understand why the prefix is fine but postfix increment does nothing. But remember in C++ we would have to have two methods instead of just one - for prefix and postfix increments. Also no errors or warnings on compile.

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• How can I build pyv8 from source on FreeBSD against the v8 port?

  - by Utkonos

  I am unable to build pyv8 from source on FreeBSD. I have installed the /usr/ports/lang/v8 port, and I'm running into the following error. It seems that pyv8 wants to build v8 itself even though v8 is already built and installed. How can I point pyv8 to the already installed location of v8? # python setup.py build Found Google v8 base on V8_HOME , update it to the latest SVN trunk at running build ==================== INFO: Installing or updating GYP... -------------------- INFO: Check out GYP from SVN ... DEBUG: make dependencies ERROR: Check out GYP from SVN failed: code=2 DEBUG: "Makefile", line 43: Missing dependency operator "Makefile", line 45: Need an operator "Makefile", line 46: Need an operator "Makefile", line 48: Need an operator "Makefile", line 50: Need an operator "Makefile", line 52: Need an operator "Makefile", line 54: Missing dependency operator "Makefile", line 56: Need an operator "Makefile", line 58: Missing dependency operator "Makefile", line 60: Need an operator "Makefile", line 62: Missing dependency operator "Makefile", line 64: Need an operator "Makefile", line 66: Missing dependency operator "Makefile", line 68: Need an operator "Makefile", line 70: Missing dependency operator "Makefile", line 72: Need an operator "Makefile", line 73: Missing dependency operator "Makefile", line 75: Need an operator "Makefile", line 77: Missing dependency operator "Makefile", line 79: Need an operator "Makefile", line 81: Missing dependency operator "Makefile", line 83: Need an operator "Makefile", line 85: Missing dependency operator "Makefile", line 87: Need an operator "Makefile", line 89: Need an operator "Makefile", line 91: Missing dependency operator "Makefile", line 93: Need an operator "Makefile", line 95: Need an operator "Makefile", line 97: Need an operator "Makefile", line 99: Missing dependency operator "Makefile", line 101: Need an operator "Makefile", line 103: Missing dependency operator "Makefile", line 105: Need an operator "Makefile", line 107: Missing dependency operator "Makefile", line 109: Need an operator "Makefile", line 111: Missing dependency operator "Makefile", line 113: Need an operator "Makefile", line 115: Missing dependency operator "Makefile", line 117: Need an operator Error expanding embedded variable. ==================== INFO: Patching the GYP scripts INFO: patch the Google v8 build/standalone.gypi file to enable RTTI and C++ Exceptions ==================== INFO: building Google v8 with GYP for x64 platform with release mode -------------------- INFO: build v8 from SVN ... DEBUG: make verifyheap=off component=shared_library visibility=on gdbjit=off liveobjectlist=off regexp=native disassembler=off objectprint=off debuggersupport=on extrachecks=off snapshot=on werror=on x64.release ERROR: build v8 from SVN failed: code=2 DEBUG: "Makefile", line 43: Missing dependency operator "Makefile", line 45: Need an operator "Makefile", line 46: Need an operator "Makefile", line 48: Need an operator "Makefile", line 50: Need an operator "Makefile", line 52: Need an operator "Makefile", line 54: Missing dependency operator "Makefile", line 56: Need an operator "Makefile", line 58: Missing dependency operator "Makefile", line 60: Need an operator "Makefile", line 62: Missing dependency operator "Makefile", line 64: Need an operator "Makefile", line 66: Missing dependency operator "Makefile", line 68: Need an operator "Makefile", line 70: Missing dependency operator "Makefile", line 72: Need an operator "Makefile", line 73: Missing dependency operator "Makefile", line 75: Need an operator "Makefile", line 77: Missing dependency operator "Makefile", line 79: Need an operator "Makefile", line 81: Missing dependency operator "Makefile", line 83: Need an operator "Makefile", line 85: Missing dependency operator "Makefile", line 87: Need an operator "Makefile", line 89: Need an operator "Makefile", line 91: Missing dependency operator "Makefile", line 93: Need an operator "Makefile", line 95: Need an operator "Makefile", line 97: Need an operator "Makefile", line 99: Missing dependency operator "Makefile", line 101: Need an operator "Makefile", line 103: Missing dependency operator "Makefile", line 105: Need an operator "Makefile", line 107: Missing dependency operator "Makefile", line 109: Need an operator "Makefile", line 111: Missing dependency operator "Makefile", line 113: Need an operator "Makefile", line 115: Missing dependency operator "Makefile", line 117: Need an operator Error expanding embedded variable. The files that are installed by the v8 port are the following (in /usr/local): bin/d8 include/v8.h include/v8-debug.h include/v8-preparser.h include/v8-profiler.h include/v8-testing.h include/v8stdint.h lib/libv8.so lib/libv8.so.1

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• Unity completely broken after upgrade to 12.10?

  - by NlightNFotis

  I am facing a very frustrating issue with my computer right now. I successfully upgraded to Ubuntu 12.10 this afternoon, but after the upgrade, the graphical user interface seems completely broken. To be more specific, I can not get the Unity bar to appear on the right. I have tried many things, including (but not limited to) purging and then reinstalling the fglrx drivers, apt-get install --reinstall ubuntu-desktop, apt-get install --reinstall unity, tried to remove the Xorg and Compiz configurations, checked to see if the Ubuntu Unity wall was enabled (it was) in ccsm, all to no avail. Could someone help me troubleshoot and essentially fix this issue? NOTE: This is the output when I try to enable unity via a terminal: compiz (core) - Info: Loading plugin: core compiz (core) - Info: Starting plugin: core unity-panel-service: no process found compiz (core) - Info: Loading plugin: reset compiz (core) - Error: Failed to load plugin: reset compiz (core) - Info: Loading plugin: ccp compiz (core) - Info: Starting plugin: ccp compizconfig - Info: Backend : gsettings compizconfig - Info: Integration : true compizconfig - Info: Profile : unity compiz (core) - Info: Loading plugin: composite compiz (core) - Info: Starting plugin: composite compiz (core) - Info: Loading plugin: opengl X Error of failed request: BadRequest (invalid request code or no such operation) Major opcode of failed request: 153 (GLX) Minor opcode of failed request: 19 (X_GLXQueryServerString) Serial number of failed request: 22 Current serial number in output stream: 22 compiz (core) - Info: Unity is not supported by your hardware. Enabling software rendering instead (slow). compiz (core) - Info: Starting plugin: opengl Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Error: Plugin initScreen failed: opengl compiz (core) - Error: Failed to start plugin: opengl compiz (core) - Info: Unloading plugin: opengl compiz (core) - Info: Loading plugin: decor compiz (core) - Info: Starting plugin: decor compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Info: Loading plugin: imgpng compiz (core) - Info: Starting plugin: imgpng compiz (core) - Info: Loading plugin: vpswitch compiz (core) - Info: Starting plugin: vpswitch compiz (core) - Info: Loading plugin: resize compiz (core) - Info: Starting plugin: resize Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Info: Loading plugin: compiztoolbox compiz (core) - Info: Starting plugin: compiztoolbox compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Info: Loading plugin: move compiz (core) - Info: Starting plugin: move compiz (core) - Info: Loading plugin: gnomecompat compiz (core) - Info: Starting plugin: gnomecompat compiz (core) - Info: Loading plugin: mousepoll compiz (core) - Info: Starting plugin: mousepoll compiz (core) - Info: Loading plugin: wall compiz (core) - Info: Starting plugin: wall compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: wall compiz (core) - Error: Failed to start plugin: wall compiz (core) - Info: Unloading plugin: wall compiz (core) - Info: Loading plugin: regex compiz (core) - Info: Starting plugin: regex compiz (core) - Info: Loading plugin: snap compiz (core) - Info: Starting plugin: snap compiz (core) - Info: Loading plugin: unitymtgrabhandles compiz (core) - Info: Starting plugin: unitymtgrabhandles compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: unitymtgrabhandles compiz (core) - Error: Failed to start plugin: unitymtgrabhandles compiz (core) - Info: Unloading plugin: unitymtgrabhandles compiz (core) - Info: Loading plugin: place compiz (core) - Info: Starting plugin: place compiz (core) - Info: Loading plugin: grid compiz (core) - Info: Starting plugin: grid Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Info: Loading plugin: animation compiz (core) - Info: Starting plugin: animation compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: animation compiz (core) - Error: Failed to start plugin: animation compiz (core) - Info: Unloading plugin: animation compiz (core) - Info: Loading plugin: fade compiz (core) - Info: Starting plugin: fade compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: fade compiz (core) - Error: Failed to start plugin: fade compiz (core) - Info: Unloading plugin: fade compiz (core) - Info: Loading plugin: session compiz (core) - Info: Starting plugin: session compiz (core) - Info: Loading plugin: expo compiz (core) - Info: Starting plugin: expo compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: expo compiz (core) - Error: Failed to start plugin: expo compiz (core) - Info: Unloading plugin: expo compiz (core) - Info: Loading plugin: ezoom compiz (core) - Info: Starting plugin: ezoom compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: ezoom compiz (core) - Error: Failed to start plugin: ezoom compiz (core) - Info: Unloading plugin: ezoom compiz (core) - Info: Loading plugin: workarounds compiz (core) - Info: Starting plugin: workarounds compiz (core) - Error: Plugin 'opengl' not loaded. Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Info: Loading plugin: scale compiz (core) - Info: Starting plugin: scale compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: scale compiz (core) - Error: Failed to start plugin: scale compiz (core) - Info: Unloading plugin: scale Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Segmentation fault (core dumped)

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• Listing both null and not null in mysql query

  - by tomasz

  Let's say I have the table NAME | ID | REF foo1 | 1 | NULL foo2 | 2 | 1234 foo2 | 3 | 567 foo1 | 4 | NULL foo3 | 5 | 89 I'd like to count all instances of NULL and NOT NULL in one query so that I can say NAME | null | not null foo1 | 0 | 2 foo2 | 2 | 0 foo3 | 0 | 1 I could run these two queries select NAME,count(*) from TABLE where REF is not null select NAME,count(*) from TABLE where REF is null But I'm sure there must be a simple way to do it in one mysql query.

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• Working with operator[] and operator=

  - by calebthorne

  Given a simple class that overloads the '[ ]' operator: class A { public: int operator[](int p_index) { return a[p_index]; } private: int a[5]; }; I would like to accomplish the following: void main() { A Aobject; Aobject[0] = 1; // Problem here } How can I overload the assignment '=' operator in this case to work with the '[ ]' operator?

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• new and delete operator overloading

  - by Angus

  I am writing a simple program to understand the new and delete operator overloading. How is the size parameter passed into the new operator? For reference, here is my code: #include<iostream> #include<stdlib.h> #include<malloc.h> using namespace std; class loc{ private: int longitude,latitude; public: loc(){ longitude = latitude = 0; } loc(int lg,int lt){ longitude -= lg; latitude -= lt; } void show(){ cout << "longitude" << endl; cout << "latitude" << endl; } void* operator new(size_t size); void operator delete(void* p); void* operator new[](size_t size); void operator delete[](void* p); }; void* loc :: operator new(size_t size){ void* p; cout << "In overloaded new" << endl; p = malloc(size); cout << "size :" << size << endl; if(!p){ bad_alloc ba; throw ba; } return p; } void loc :: operator delete(void* p){ cout << "In delete operator" << endl; free(p); } void* loc :: operator new[](size_t size){ void* p; cout << "In overloaded new[]" << endl; p = malloc(size); cout << "size :" << size << endl; if(!p){ bad_alloc ba; throw ba; } return p; } void loc :: operator delete[](void* p){ cout << "In delete operator - array" << endl; free(p); } int main(){ loc *p1,*p2; int i; cout << "sizeof(loc)" << sizeof(loc) << endl; try{ p1 = new loc(10,20); } catch (bad_alloc ba){ cout << "Allocation error for p1" << endl; return 1; } try{ p2 = new loc[10]; } catch(bad_alloc ba){ cout << "Allocation error for p2" << endl; return 1; } p1->show(); for(i = 0;i < 10;i++){ p2[i].show(); } delete p1; delete[] p2; return 0; }

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• Null check error message as "is null" or "was null"

  - by Timo Westkämper

  When doing null checks in Java code, and you throw IllegalArgumentExceptions for null values, what kind of message template do you use? We tend to use something like this public User getUser(String username){ if (username == null){ throw new IllegalArgumentException("username is null"); } // ... } What is better : "is null" or "was null", and why? For me "is null" feels more natural.

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• Null-coalescing operator and operator && in C#

  - by abatishchev

  Is it possible to use together any way operator ?? and operator && in next case: bool? Any { get { var any = this.ViewState["any"] as bool?; return any.HasValue ? any.Value && this.SomeBool : any; } } This means next: if any is null then this.Any.HasValue return false if any has value, then it returns value considering another boolean property, i.e. Any && SomeBool

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• So which null equals this null, that null? maybe this null, or is it this null?

  - by GrumpyOldDBA

  Tuning takes many routes and I get into some interesting situations and often make some exciting finds, see http://sqlblogcasts.com/blogs/grumpyolddba/archive/2010/05/17/just-when-you-thought-it-was-safe.aspx for an example. Today I encountered a multitude of Foreign Key constraints on a table, now FKs are often candidates for indexes and as none of the defined keys had an index it required a closer look. I view foreign key constraints as somewhat of a pain, excessive keys can cause excessive related...(read more)

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• C++ segmentation error when first parameter is null in comparison operator overload

  - by user1774515

  I am writing a class called Word, that handles a c string and overloads the <, , <=, = operators. word.h: friend bool operator<(const Word &a, const Word &b); word.cc: bool operator<(const Word &a, const Word &b) { if(a == NULL && b == NULL) return false; if(a == NULL) return true; if(b == NULL) return false; return a.wd < b.wd; //wd is a valid c string } main: char* temp = NULL; //EDIT: i was mistaken, temp is a char pointer Word a("blah"); //a.wd = [b,l,a,h] cout << (temp<a); i get a segmentation error before the first line of the operator< method after the last line in the main. I can correct the problem by writing cout << (a>temp); where the operator> is similarly defined and i get no errors. but my assignment requires (temp < a) to work so this is where i ask for help. EDIT: i made a mistake the first time and i said temp was of type Word, but it is actually of type char*. so i assume that the compiler converts temp to a Word using one of my constructors. i dont know which one it would use and why this would work since the first parameter is not Word. here is the constructor i think is being used to make the Word using temp: Word::Word(char* c, char* delimeters=NULL) { char *temporary = "\0"; if(c == NULL) c = temporary; check(stoppers!=NULL, "(Word(char*,char*))NULL pointer"); //exits the program if the expression is false if(strlen(c) == 0) size = DEFAULT_SIZE; //10 else size = strlen(c) + 1 + DEFAULT_SIZE; wd = new char[size]; check(wd!=NULL, "Word(char*,char*))heap overflow"); delimiters = new char[strlen(stoppers) + 1]; //EDIT: changed to [] check(delimiters!=NULL,"Word(char*,char*))heap overflow"); strcpy(wd,c); strcpy(delimiters,stoppers); count = strlen(wd); } wd is of type char* thanks for looking at this big question and trying to help. let me know if you need more code to look at

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• Check parameters annotated with @Nonnull for null?

  - by David Harkness

  We've begun using FindBugs with and annotating our parameters with @Nonnull appropriately, and it works great to point out bugs early in the cycle. So far we have continued checking these arguments for null using Guava's checkNotNull, but I would prefer to check for null only at the edges--places where the value can come in without having been checked for null, e.g., a SOAP request. // service layer accessible from outside public Person createPerson(@CheckForNull String name) { return new Person(Preconditions.checkNotNull(name)); } ... // internal constructor accessed only by the service layer public Person(@Nonnull String name) { this.name = Preconditions.checkNotNull(name); // remove this check? } I understand that @Nonnull does not block null values itself. However, given that FindBugs will point out anywhere a value is transferred from an unmarked field to one marked @Nonnull, can't we depend on it to catch these cases (which it does) without having to check these values for null everywhere they get passed around in the system? Am I naive to want to trust the tool and avoid these verbose checks? Bottom line: While it seems safe to remove the second null check below, is it bad practice? This question is perhaps too similar to Should one check for null if he does not expect null, but I'm asking specifically in relation to the @Nonnull annotation.

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• MySql query optimization help

  - by rohitgu

  I have few queries and am not able to figure out how to optimize them, QUERY 1 select * from t_twitter_tracking where classified is null and tweetType='ENGLISH' order by id limit 500; QUERY 2 Select count(*) as cnt, DATE_FORMAT(CONVERT_TZ(wrdTrk.createdOnGMTDate,'+00:00','+05:30'),'%Y-%m-%d') as dat from t_twitter_tracking wrdTrk where wrdTrk.word like ('dell') and CONVERT_TZ(wrdTrk.createdOnGMTDate,'+00:00','+05:30') between '2010-12-12 00:00:00' and '2010-12-26 00:00:00' group by dat; Both these queries run on the same table, CREATE TABLE `t_twitter_tracking` ( `id` BIGINT(20) NOT NULL AUTO_INCREMENT, `word` VARCHAR(200) NOT NULL, `tweetId` BIGINT(100) NOT NULL, `twtText` VARCHAR(800) NULL DEFAULT NULL, `language` TEXT NULL, `links` TEXT NULL, `tweetType` VARCHAR(20) NULL DEFAULT NULL, `source` TEXT NULL, `sourceStripped` TEXT NULL, `isTruncated` VARCHAR(40) NULL DEFAULT NULL, `inReplyToStatusId` BIGINT(30) NULL DEFAULT NULL, `inReplyToUserId` INT(11) NULL DEFAULT NULL, `rtUsrProfilePicUrl` TEXT NULL, `isFavorited` VARCHAR(40) NULL DEFAULT NULL, `inReplyToScreenName` VARCHAR(40) NULL DEFAULT NULL, `latitude` BIGINT(100) NOT NULL, `longitude` BIGINT(100) NOT NULL, `retweetedStatus` VARCHAR(40) NULL DEFAULT NULL, `statusInReplyToStatusId` BIGINT(100) NOT NULL, `statusInReplyToUserId` BIGINT(100) NOT NULL, `statusFavorited` VARCHAR(40) NULL DEFAULT NULL, `statusInReplyToScreenName` TEXT NULL, `screenName` TEXT NULL, `profilePicUrl` TEXT NULL, `twitterId` BIGINT(100) NOT NULL, `name` TEXT NULL, `location` VARCHAR(100) NULL DEFAULT NULL, `bio` TEXT NULL, `url` TEXT NULL COLLATE 'latin1_swedish_ci', `utcOffset` INT(11) NULL DEFAULT NULL, `timeZone` VARCHAR(100) NULL DEFAULT NULL, `frenCnt` BIGINT(20) NULL DEFAULT '0', `createdAt` DATETIME NULL DEFAULT NULL, `createdOnGMT` VARCHAR(40) NULL DEFAULT NULL, `createdOnServerTime` DATETIME NULL DEFAULT NULL, `follCnt` BIGINT(20) NULL DEFAULT '0', `favCnt` BIGINT(20) NULL DEFAULT '0', `totStatusCnt` BIGINT(20) NULL DEFAULT NULL, `usrCrtDate` VARCHAR(200) NULL DEFAULT NULL, `humanSentiment` VARCHAR(30) NULL DEFAULT NULL, `replied` BIT(1) NULL DEFAULT NULL, `replyMsg` TEXT NULL, `classified` INT(32) NULL DEFAULT NULL, `createdOnGMTDate` DATETIME NULL DEFAULT NULL, `locationDetail` TEXT NULL, `geonameid` INT(11) NULL DEFAULT NULL, `country` VARCHAR(255) NULL DEFAULT NULL, `continent` CHAR(2) NULL DEFAULT NULL, `placeLongitude` FLOAT NULL DEFAULT NULL, `placeLatitude` FLOAT NULL DEFAULT NULL, PRIMARY KEY (`id`), INDEX `id` (`id`, `word`), INDEX `createdOnGMT_index` (`createdOnGMT`) USING BTREE, INDEX `word_index` (`word`) USING BTREE, INDEX `location_index` (`location`) USING BTREE, INDEX `classified_index` (`classified`) USING BTREE, INDEX `tweetType_index` (`tweetType`) USING BTREE, INDEX `getunclassified_index` (`classified`, `tweetType`) USING BTREE, INDEX `timeline_index` (`word`, `createdOnGMTDate`, `classified`) USING BTREE, INDEX `createdOnGMTDate_index` (`createdOnGMTDate`) USING BTREE, INDEX `locdetail_index` (`country`, `id`) USING BTREE, FULLTEXT INDEX `twtText_index` (`twtText`) ) COLLATE='utf8_general_ci' ENGINE=MyISAM ROW_FORMAT=DEFAULT AUTO_INCREMENT=12608048; The table has more than 10 million records. How can I optimize it?

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• PHP: why is this null different from the other null

  - by matthy

  hi i tried 2 things what should be the same however it my testing says different does anyone know why the only thing i do is put it in a variable... if ($_SESSION[$something] === null) echo("this is null"); $_SESSION[$something] does not exists so it indeed says: "this is null". now look at this $theSession = $_SESSION[$something]; if (theSession === null) echo("this is null"); now it does not say "this is null" while it should be exactly the same right?

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• C++: call original definition of operator equals

  - by Luis Daniel

  I am overloading the operator equals (==) as show bellow: #include <string> #include <algorithm> bool operator == (std::string str1, std::string str2) { std::transform(str1.begin(), str1.end(), str1.begin(), ::tolower); std::transform(str2.begin(), str2.end(), str2.begin(), ::tolower); return (str1 == str2); } but, the problem appear on line return (str1 == str2), because operator == is called recursively. So, how can I call the original definition for operator equals (not the overloaded) ? Best regards

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• Difference between null==object and object==null

  - by priyank.mp

  Hi I would like to know diff between the above comparisons? I am getting null pointer exception when I check object.getItems() == null. But if I change it to null == object.getItems(), it workes fine. I did look into this http://stackoverflow.com/questions/2938476/what-is-the-difference-between-null-object-and-objectnull-closed But I didnt get satisfactory answer.

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• "Null" is null or not an object error in IE javascript

  - by user89691

  The following code executes fine in Firefox and Chrome, but gives an error: 'null' is null or not an object when executed in Internet Explorer. if (xmlhttp.responseXML != null) { var xmlDoc = xmlhttp.responseXML.documentElement ; var ResultNodes = xmlDoc.getElementsByTagName ("Result") ; <---- error here if (ResultNodes != null) { (I would have thought the line after the one indicated would be more likely to return the error but the debugger says the run-time error is at the line indicated) Any ideas why?

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• "Null" is null or not an object error in IE javascript

  - by rossmcm

  The following code executes fine in Firefox and Chrome, but gives an error: 'null' is null or not an object when executed in Internet Explorer. if (xmlhttp.responseXML != null) { var xmlDoc = xmlhttp.responseXML.documentElement ; var ResultNodes = xmlDoc.getElementsByTagName ("Result") ; <---- error here if (ResultNodes != null) { (I would have thought the line after the one indicated would be more likely to return the error but the debugger says the run-time error is at the line indicated) Any ideas why?

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