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  • LIKE operator with $variable

    - by skarama
    This is my first question here and I hope it is simple enough to get a quick answer! Basically, I have the following code: $variable = curPageURL(); $query = 'SELECT * FROM `tablename` WHERE `columnname` LIKE '$variable' ; If I echo the $variable, it prints the current page's url( which is a javascript on my page) Ultimately, what I want, is to be able to make a search for which the search-term is the current page's url, with wildcards before and after. I am not sure if this is possible at all, or if I simply have a syntax error, because I get no errors, simply no result! I tried : $query = 'SELECT * FROM `tablename` WHERE `columnname` LIKE '"echo $variable" ' ; But again, I'm probably missing or using a misplaced ' " ; etc. Please tell me what I'm doing wrong!

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  • Conditional operator in if-statement?

    - by Pindatjuh
    I've written the following if-statement in Java: if(methodName.equals("set" + this.name) || isBoolean() ? methodName.equals("is" + this.name) : methodName.equals("get" + this.name)) { ... } Is this a good practice to write such expressions in if, to separate state from condition? And can this expression be simplified?

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  • Ternary operator in if-statement?

    - by Pindatjuh
    I've written the following if-statement in Java: if(methodName.equals("set" + this.name) || isBoolean() ? methodName.equals("is" + this.name) : methodName.equals("get" + this.name)) { ... } Is this a good practice to write such expressions in if, to separate state from condition? And can this expression be simplified?

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  • The unary increment operator in pointer arithmetic

    - by RhymesWithDuck
    Hello, this is my first post. I have this function for reversing a string in C that I found. void reverse(char* c) { if (*c != 0) { reverse(c + 1); } printf("%c",*c); } It works fine but if I replace: reverse(c + 1); with: reverse(++c); the first character of the original string is truncated. My question is why would are the statements not equivalent in this instance? Thanks

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  • post increment operator java

    - by srandpersonia
    I can't make heads or tails of the following code from "java puzzlers" by joshua bloch. public class Test22{ public static void main(String args[]){ int j=0; for(int i=0;i<100;i++){ j=j++; } System.out.println(j); //prints 0 int a=0,b=0; a=b++; System.out.println(a); System.out.println(b); //prints 1 } } I can't get the part where j prints 0. According to the author, j=j++ is similar to temp=j; j=j+1; j=temp; But a=b++ makes b 1. So it should've evaluated like this, a=b b=b+1 By following the same logic, shouldn't j=j++ be evaluated as, j=j j=j+1 Where does the temp come into picture here? Any explanations would be much appreciated. << I'm breaking my head over this. ;) Thanks in advance.

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  • Is Operator Overloading supported in C

    - by caramel23
    Today when I was reading about LCC(windows) compiler I find out it has the implemention for operator overloading . I'm puzzled because after a bit of googling , it has been confirm that operator overloading ain't support in standard C , but I read some people's comment mentioning LCC is ANSI-compliant . So my real question is , is LCC really standard C or it's just like objective-c , a C variant with object-oriented feature ?

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  • Implicit and Explicit implementations for Multiple Interface inheritance

    Following C#.NET demo explains you all the scenarios for implementation of Interface methods to classes. There are two ways you can implement a interface method to a class. 1. Implicit Implementation 2. Explicit Implementation. Please go though the sample. using System;   namespace ImpExpTest { class Program { static void Main(string[] args) { C o3 = new C(); Console.WriteLine(o3.fu());   I1 o1 = new C(); Console.WriteLine(o1.fu());   I2 o2 = new C(); Console.WriteLine(o2.fu());   var o4 = new C(); //var is considered as C Console.WriteLine(o4.fu());   var o5 = (I1)new C(); //var is considered as I1 Console.WriteLine(o5.fu());   var o6 = (I2)new C(); //var is considered as I2 Console.WriteLine(o6.fu());   D o7 = new D(); Console.WriteLine(o7.fu());   I1 o8 = new D(); Console.WriteLine(o8.fu());   I2 o9 = new D(); Console.WriteLine(o9.fu()); } }   interface I1 { string fu(); }   interface I2 { string fu(); }   class C : I1, I2 { #region Imicitly Defined I1 Members public string fu() { return "Hello C"; } #endregion Imicitly Defined I1 Members   #region Explicitly Defined I1 Members   string I1.fu() { return "Hello from I1"; }   #endregion Explicitly Defined I1 Members   #region Explicitly Defined I2 Members   string I2.fu() { return "Hello from I2"; }   #endregion Explicitly Defined I2 Members }   class D : C { #region Imicitly Defined I1 Members public string fu() { return "Hello from D"; } #endregion Imicitly Defined I1 Members } }.csharpcode, .csharpcode pre{ font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/}.csharpcode pre { margin: 0em; }.csharpcode .rem { color: #008000; }.csharpcode .kwrd { color: #0000ff; }.csharpcode .str { color: #006080; }.csharpcode .op { color: #0000c0; }.csharpcode .preproc { color: #cc6633; }.csharpcode .asp { background-color: #ffff00; }.csharpcode .html { color: #800000; }.csharpcode .attr { color: #ff0000; }.csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em;}.csharpcode .lnum { color: #606060; }Output:-Hello C Hello from I1 Hello from I2 Hello C Hello from I1 Hello from I2 Hello from D Hello from I1 Hello from I2 span.fullpost {display:none;}

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  • Is my method for avoiding dynamic_cast<> faster than dynamic_cast<> itself ?

    - by ereOn
    Hi, I was answering a question a few minutes ago and it raised to me another one: In one of my projects, I do some network message parsing. The messages are in the form of: [1 byte message type][2 bytes payload length][x bytes payload] The format and content of the payload are determined by the message type. I have a class hierarchy, based on a common class Message. To instanciate my messages, i have a static parsing method which gives back a Message* depending on the message type byte. Something like: Message* parse(const char* frame) { // This is sample code, in real life I obviously check that the buffer // is not NULL, and the size, and so on. switch(frame[0]) { case 0x01: return new FooMessage(); case 0x02: return new BarMessage(); } // Throw an exception here because the mesage type is unknown. } I sometimes need to access the methods of the subclasses. Since my network message handling must be fast, I decived to avoid dynamic_cast<> and I added a method to the base Message class that gives back the message type. Depending on this return value, I use a static_cast<> to the right child type instead. I did this mainly because I was told once that dynamic_cast<> was slow. However, I don't know exactly what it really does and how slow it is, thus, my method might be as just as slow (or slower) but far more complicated. What do you guys think of this design ? Is it common ? Is it really faster than using dynamic_cast<> ? Any detailed explanation of what happen under the hood when one use dynamic_cast<> is welcome !

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  • Implicit and Explicit implementations for Multiple Interface inheritance

    Following C#.NET demo explains you all the scenarios for implementation of Interface methods to classes. There are two ways you can implement a interface method to a class. 1. Implicit Implementation 2. Explicit Implementation. Please go though the sample. using System; namespace ImpExpTest {     class Program     {         static void Main(string[] args)         {             C o3 = new C();             Console.WriteLine(o3.fu());             I1 o1 = new C();             Console.WriteLine(o1.fu());             I2 o2 = new C();             Console.WriteLine(o2.fu());             var o4 = new C();       //var is considered as C             Console.WriteLine(o4.fu());             var o5 = (I1)new C();   //var is considered as I1             Console.WriteLine(o5.fu());             var o6 = (I2)new C();   //var is considered as I2             Console.WriteLine(o6.fu());             D o7 = new D();             Console.WriteLine(o7.fu());             I1 o8 = new D();             Console.WriteLine(o8.fu());             I2 o9 = new D();             Console.WriteLine(o9.fu());         }     }     interface I1     {         string fu();     }     interface I2     {         string fu();     }     class C : I1, I2     {         #region Imicitly Defined I1 Members         public string fu()         {             return "Hello C"         }         #endregion Imicitly Defined I1 Members         #region Explicitly Defined I1 Members         string I1.fu()         {             return "Hello from I1";         }         #endregion Explicitly Defined I1 Members         #region Explicitly Defined I2 Members         string I2.fu()         {             return "Hello from I2";         }         #endregion Explicitly Defined I2 Members     }     class D : C     {         #region Imicitly Defined I1 Members         public string fu()         {             return "Hello from D";         }         #endregion Imicitly Defined I1 Members     } } Output:- Hello C Hello from I1 Hello from I2 Hello C Hello from I1 Hello from I2 Hello from D Hello from I1 Hello from I2 span.fullpost {display:none;}

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  • Double Buffering for Game objects, what's a nice clean generic C++ way?

    - by Gary
    This is in C++. So, I'm starting from scratch writing a game engine for fun and learning from the ground up. One of the ideas I want to implement is to have game object state (a struct) be double-buffered. For instance, I can have subsystems updating the new game object data while a render thread is rendering from the old data by guaranteeing there is a consistent state stored within the game object (the data from last time). After rendering of old and updating of new is finished, I can swap buffers and do it again. Question is, what's a good forward-looking and generic OOP way to expose this to my classes while trying to hide implementation details as much as possible? Would like to know your thoughts and considerations. I was thinking operator overloading could be used, but how do I overload assign for a templated class's member within my buffer class? for instance, I think this is an example of what I want: doublebuffer<Vector3> data; data.x=5; //would write to the member x within the new buffer int a=data.x; //would read from the old buffer's x member data.x+=1; //I guess this shouldn't be allowed If this is possible, I could choose to enable or disable double-buffering structs without changing much code. This is what I was considering: template <class T> class doublebuffer{ T T1; T T2; T * current=T1; T * old=T2; public: doublebuffer(); ~doublebuffer(); void swap(); operator=()?... }; and a game object would be like this: struct MyObjectData{ int x; float afloat; } class MyObject: public Node { doublebuffer<MyObjectData> data; functions... } What I have right now is functions that return pointers to the old and new buffer, and I guess any classes that use them have to be aware of this. Is there a better way?

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  • Is it ok to dynamic cast "this" as a return value?

    - by Panayiotis Karabassis
    This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

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  • How do you pronounce the '...' operator

    - by Uri
    Now, in c++ '...' became a first class operator. In speech, how do you pronounce it? So far I've heard: dot dot dot triple dot ellipsis related: Is it OK to replace ... with ellipsis in writing? e.g. "The ellipsis operator expands the pack" EDIT (clarification): We are all aware that '...' as a punctuation mark is indeed called ellipsis. But in the context of C++ we don't pronounce the names of the punctuation mark. For example, the '&' operator, depends on the context is pronounced as 'and', 'bitwise and', 'address of', 'logical and' (when && is used), or 'reference'. It is rarely pronounced as 'ampersand'. In speeches, I've a feeling that 'dot dot dot' is used more often. For example: http://channel9.msdn.com/Events/GoingNative/GoingNative-2012/Variadic-Templates-are-Funadic (an excellent presentation about variadic templates). On the other hand, 'dot dot dot' is awkward hard to pronouce ('d' and 't' are both pronounce with the tongue). Can we pronounce it 'unpack'?

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  • Distinct operator in Linq

    - by Jalpesh P. Vadgama
    Linq operator provides great flexibility and easy way of coding. Let’s again take one more example of distinct operator. As name suggest it will find the distinct elements from IEnumerable. Let’s take an example of array in console application and then we will again print array to see is it working or not. Below is the code for that. In this application I have integer array which contains duplicate elements and then I will apply distinct operator to this and then I will print again result of distinct operators to actually see whether its working or not. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Experiment { class Program { static void Main(string[] args) { int[] intArray = { 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5 }; var uniqueIntegers = intArray.Distinct(); foreach (var uInteger in uniqueIntegers) { Console.WriteLine(uInteger); } Console.ReadKey(); } } } Below is output as expected.. That’s cool..Stay tuned for more.. Happy programming. Technorati Tags: Linq,Distinct

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  • Play music by Operator in asterisk?

    - by Rev
    Hi I want in call duration between operator and caller,play sound for operator(something like hold music). But in order to play this sound, operator must dial unique code and then sound will be play for caller, and caller only hear that sound file! After that (sound fully played), caller back to operator's queue or something like this. So is this possible to do or not? (if possible, post dial-plan for this too)

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  • Play music by Operator in asterisk?

    - by Rev
    Hi I want in call duration between operator and caller,play sound for operator(something like hold music). But in order to play this sound, operator must dial unique code and then sound will be play for caller, and caller only hear that sound file! After that (sound fully played), caller back to operator's queue or something like this. So is this possible to do or not? (if possible, post dial-plan for this too)

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  • how to refer to the current struct in an overloaded operator?

    - by genesys
    Hi! I have a struct for which i want to define a relative order by defining < , , <= and = operators. actually in my order there won't be any equality, so if one struct is not smaller than another, it's automatically larger. I defined the first operator like this: struct MyStruct{ ... ... bool operator < (const MyStruct &b) const {return (somefancycomputation);} }; now i'd like to define the other operators based on this operator, such that <= will return the same as < and the other two will simply return the oposite. so for example for the operator i'd like to write something like bool operator > (const MyStruct &b) const {return !(self<b);} but i don't know how to refere to this 'self' since i can refere only to the fields inside the current struct. whole is in C++ hope my question was understandable :) thank you for the help!

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  • Defining < for STL sort algorithm - operator overload, functor or standalone function?

    - by Andy
    I have a stl::list containing Widget class objects. They need to be sorted according to two members in the Widget class. For the sorting to work, I need to define a less-than comparator comparing two Widget objects. There seems to be a myriad of ways to do it. From what I can gather, one can either: a. Define a comparison operator overload in the class: bool Widget::operator< (const Widget &rhs) const b. Define a standalone function taking two Widgets: bool operator<(const Widget& lhs, const Widget& rhs); And then make the Widget class a friend of it: class Widget { // Various class definitions ... friend bool operator<(const Widget& lhs, const Widget& rhs); }; c. Define a functor and then include it as a parameter when calling the sort function: class Widget_Less : public binary_function<Widget, Widget, bool> { bool operator()(const Widget &lhs, const Widget& rhs) const; }; Does anybody know which method is better? In particular I am interested to know if I should do 1 or 2. I searched the book Effective STL by Scott Meyer but unfortunately it does not have anything to say about this. Thank you for your reply.

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  • [C++] Can all/any struct assignment operator be Overloaded? (and specifically struct tm = sql::Resu

    - by Luke Mcneice
    Hi all, Generally, i was wondering if there was any exceptions of types that cant have thier assignment operator overloaded. Specifically, I'm wanting to overload the assignment operator of a tm struct, (time.h) so i can assign a sql::ResultSet to it. I have already have the conversion logic: sscanf(sqlresult->getString("StoredAt").c_str(),"%d-%d-%d %d:%d:%d",&TempTimeStruct->tm_year,&TempTimeStruct->tm_mon,&TempTimeStruct->tm_mday,&TempTimeStruct->tm_hour,&TempTimeStruct->tm_min,&TempTimeStruct->tm_sec); //populating the struct I tried the overload with this: tm& tm::operator=(sql::ResultSet & results) { //CODE return *this; } however VS08 reports: error C2511: 'tm &tm::operator =(sql::ResultSet &)' : overloaded member function not found in 'tm'

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  • What is the purpose of Java's unary plus operator?

    - by Syntactic
    Java's unary plus operator appears to have come over from C, via C++. As near as I can tell, it has the following effects: promotes its operand to int, if it's not already an int or wider unboxes its operand, if it's a wrapper object complicates slightly the parsing of evil expressions containing large numbers of consecutive plus signs It seems to me that there are better (or, at least, clearer) ways to do all of these things. In this SO question, concerning the counterpart operator in C#, someone said that "It's there to be overloaded if you feel the need." But in Java, one cannot overload any operator. So does this operator exist in Java just because it existed in C++?

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