operator-keyword

In languages such as... well anything, both operators for < and <= (and their opposites) exist. Which would be faster, and how are they interpreted? if (x <= y) { blah; } or if (x < y + 1) { blah; } Assuming no compiler optimizations (big assumption), the first will be faster, as <= is implemented by a single jle instruction, where as the latter requires an addition followed by a jl instruction. http://en.wikibooks.org/wiki/X86_Assembly/Control_Flow#Jump_if_Less I wouldn't worry about this at all as far as performance goes. Using C as an example, on a simple test I ran with GCC 4.5.1 targeting

I have 2 classes which represent a matrix: 1. RegularMatrix - O(n^2) representation 2. SparseMatrix - a matrix that is represented as linked list (without zeros). lets say i have: RegularMatrix a; SparseMatrix b; i want to be able to do: a+b; and also: b+a; so i'm overloading the + operator. My question is, since I want the addition to be commutative (a+b = b+a), do i need to implement 2 overloadings, one for each case? RegularMatrix operator+(const RegualarMatrix &, const SparseMatrix &); RegularMatrix operator+(const SparseMatrix & ,const RegualarMatrix &); or is there a general form which

Possible Duplicate: Where should non-member operator overloads be placed? While browsing on SO, I often find questions or answer that involves overloading/defining a std::ostream& operator<<(std::ostream& os, const Foo& foo) or a Foo operator+(const Foo& l, const Foo& r) . While I know how and when (not) to write these operators, I'm confused about the namespace thing. If I have the following class: namespace bar { class Foo {}; } In which namespace should I write the different operator definitions ? // Should it be this namespace bar { std::ostream& operator<<(std::ostream& os, const Foo& foo

My question is in regards to friend functions as well as overloading the << and >>. From my understanding I thought friend functions could (and should) access private member variables directly. However in the case I have here the compiler would only accept my .cxx file when I used "get" functions to obtain each private variable. Here is my header file class BigNum public: // CONSTRUCTORS and DESTRUCTORS BigNum(); BigNum(int num, size_t optional_base = 10); BigNum(const char strin[], size_t optional_base = 10); // MEMBER FUNCTIONS size_t get_digit(size_t index) const; size_t get_used() const;

This question already has an answer here: What is the meaning of prepended double colon “::”? 9 answers I've seen this a few times now, and I've been scratching my head wondering why... As an example: (http://www.codeguru.com/forum/showthread.php?t=377394) void LeftClick ( ) { INPUT Input={0}; // left down Input.type = INPUT_MOUSE; Input.mi.dwFlags = MOUSEEVENTF_LEFTDOWN; ::SendInput(1,&Input,sizeof(INPUT)); // left up ::ZeroMemory(&Input,sizeof(INPUT)); Input.type = INPUT_MOUSE; Input.mi.dwFlags = MOUSEEVENTF_LEFTUP; ::SendInput(1,&Input,sizeof(INPUT)); } This example works without the ::

Is there a reason why passing a reference to a std::map as const causes the [] operator to break? I get this compiler error (gcc 4.2) when I use const: error: no match for ‘operator[]’ in ‘map[name]’ Here's the function prototype: void func(const char ch, std::string &str, const std::map<std::string, std::string> &map); And, I should mention that there is no problem when I remove the const keyword in front of std::map . If I've been instructed correctly, the [] operator will actually insert a new pair into the map if it doesn't find the key, which would of course explain why this happens, but