How to operate different class just one functionsone
class A {}; class B {}; class C {}; class D {}; //A+B , A+C, B+C , A+D, D+C namely all of these combinations will be possible just one functions ...
operator-keyword
Implementing operator< in C++
I have a class with a few numeric fields such as: class Class1 { int a; int b; int c; public: // constructor and so on... bool operator<(const Class1& other) const; }; I need to use objects of this class as a key in an std::map. I therefore implement operator<. What is the simplest implementation of operator< to us...
User Defined Conversions in C++
Recently, I was browsing through my copy of the C++ Pocket Reference from O'Reilly Media, and I was surprised when I came across a brief section and example regarding user-defined conversion for user-defined types: #include <iostream> class account { private: double balance; public: account (double b) { balanc...
c++ input stream not waiting for input with extraction operator overload
This problem is annoying me. Instead of waiting for input, it just closes. I've been trying to figure this out for a while now. Any ideas? istream& operator>>(istream& is, Account &a) { cout << "Enter an accoutn number: "; is >> a.accountNo; cout << endl; cout << "Balance: "; is >> a.bal; retur...
Overloading + to add two pointers
I have a String class and I want to overload + to add two String* pointers. something like this doesn't work: String* operator+(String* s1, String* s2); Is there any way to avoid passing by reference. Consider this example: String* s1 = new String("Hello"); String* s2 = new String("World"); String* s3 = s1 + s2; I need this kind o...
no match for operator= using a std::vector
I've got a class declared like this: class Level { private: std::vector<mapObject::MapObject> features; (...) }; and in one of its member functions I try to iterate through that vector like this: vector<mapObject::MapObject::iterator it; for(it=features.begin(); it<features.end(); it++) { /* loop code */ } This ...
Type casting Collections using Conversion Operators
The below code gives me User-defined conversion must convert to or from enclosing type, while snippet #2 doesn't... It seems that a user-defined conversion routine must convert to or from the class that contains the routine. What are my alternatives? Explicit operator as extension method? Anything else? public static explicit oper...
operator std::string() const??
Can somebody tell me what precisely operator std::string() stands for? Thanks in advance! ...
Why does javascript's "in" operator return true when testing if 0 exists in an array that doesn't contain 0?
Why does the "in" operator in Javascript return true when testing if "0" exists in array, even when the array doesn't appear to contain "0"? For example, this returns true, and makes sense: var x = [1,2]; 1 in x; // true This returns false, and makes sense: var x = [1,2]; 3 in x; // false However this returns true, and I don't und...
C++ Tracking primitive type value change
i have a complex program with weird bug that some int value is down to zero unexpectedly. so i want tracking this built-in type value, then i could debug easily. to do that, i made following ValueWatcher template class so i could track almost changes of value except when ValueWatcher is dereferencing. (i made these dereferencing operat...
assignment operator overloading problem
This issue has me confused. The first piece of code works fine without crashing, it assigns s1 to s2 perfectly fine. But the second group of code causes the program to crash. Anyone have any idea on why this is happening or what the problem could be? Code 1:(works) s1.add(10, 30, 25, "Test Screen", false); s1.add(13, 10, 5, "Nam...
Does the ``??`` operator use shortcircuiting?
Does the ?? operator in C# use shortcircuiting when evaluating? var result = myObject ?? ExpressionWithSideEffects(); When myObject is non-null, the result of ExpressionWithSideEffects() is not used, but will ExpressionWithSideEffects() be skipped completely? ...
Haskell operator vs function precedence
Hi I am trying to verify something for myself about operator and function precedence in Haskell. For instance, the following code list = map foo $ xs can be rewritten as list = (map foo) $ (xs) and will eventually be list = map foo xs My question used to be, why the first formulation would not be rewritten as list = (map fo...
'No matching function' -error when trying to insert to a set (c++)
I have the following code: class asd { public: int b; asd() { b = rand() % 10; } bool operator<(asd &other) { return b < other.b; } }; int main() { asd * c; c = new asd(); set <asd> uaua; uaua.insert(c); } Yet when running it, I get this error: main.cpp|36|error: no matching function for...
PHP - What could the Object structure be, when we use two object operator tokens like this -> -> ?
I've seen something like this: echo ($hello->somethingA->somethingB); What does this mean? I will try to make my question more clear: When we have $domain->something; (we are accessing something PROPERTY of $domain OBJECT. precise? When we have $domain->something->run(); we are telling our something PROPERTY of $DOMAIN OBJECT to ...
How to handle combination []+= for auto-vivifying hash in Ruby?
In order to implement auto-vivification of Ruby hash, one can employ the following class class AutoHash < Hash def initialize(*args) super() @update, @update_index = args[0][:update], args[0][:update_key] unless args.empty? end def [](k) if self.has_key?k super(k) else AutoHash.new(:update => self, :u...
Conditional operator and assignment operator in C
On http://groups.google.co.in/group/comp.lang.c/browse_thread/thread/bfb312ad902d94eb/74dcdcacce777679?lnk=gst&q=conditional+operator#74dcdcacce777679 There is an answer given for a question why (A%2==0)?A=0:A=1 gives error. The thing I don't understand that when do we use (precedence and associativty) and we use C grammar to parse...
Understanding infix method call and cons operator(::) in Scala
Hello, I'm quite new to Scala programming language, and was trying something out stucked in my mind while I was following the lecture notes at here. I think I couldn't really understand how cons operator works, here are some things I tried: I've created a pseudo-random number generator, then tried to create a list of one random value...
>!= PHP operator, how to write not equal to or greater than?
How can I write not greater-than-or-equal-to in php? Is it >!=? ...
php timestamp not logical?
Hi, I loop through an array looking at the date (as key) and if it is before the event date I use the rating value (as value). Basically I'm looking for the closest value in the array before the event date. My code: $ratingData = $player->ratingData; foreach ($ratingData as $ratingDate => $ratingValue) { list($year, $month, $day) =...