operator-overloading

问题 I recently start teaching myself game programming. Someone recommend me to start with Python and I got the book "Beginning game development with Python and Pygame: From novice to professional". I got to a part where they teach about Vectors and creating a Vector2 class. Everything was going well until I tried to overload the division operator. My code goes like this: class Vector2(object): def __init__(self, x=0.0, y=0.0): self.x = x self.y = y def __str__(self): return "(%s, %s)"%(self.x,

问题 I have next code: #include <iostream> #include <algorithm> #include <map> #include <iterator> //namespace std //{ std::ostream& operator << ( std::ostream& out, const std::pair< size_t, size_t >& rhs ) { out << rhs.first << ", " << rhs.second; return out; } //} int main() { std::map < size_t, size_t > some_map; // fill some_map with random values for ( size_t i = 0; i < 10; ++i ) { some_map[ rand() % 10 ] = rand() % 100; } // now I want to output this map std::copy( some_map.begin(), some_map

问题 I am trying to implement a generic operator like so: class Foo { public static T operator +<T>(T a, T b) { // Do something with a and b that makes sense for operator + here } } Really what I'm trying to do is gracefully handle inheritance. With a standard operator + in Foo, where T is instead "Foo", if anyone is derived from Foo (say Bar inherits Foo), then a Bar + Bar operation will still return a Foo. I was hoping to solve this with a generic operator +, but I just get a syntax error for

问题 I see questions on SO every so often about overloading the comma operator in C++ (mainly unrelated to the overloading itself, but things like the notion of sequence points), and it makes me wonder: When should you overload the comma? What are some examples of its practical uses? I just can't think of any examples off the top of my head where I've seen or needed to something like foo, bar; in real-world code, so I'm curious as to when (if ever) this is actually used. 回答1: Let's change the

问题 I have read couple of the questions regarding my problem on StackOverflow.com now, and none of it seems to solve my problem. Or I maybe have done it wrong... The overloaded << works if I make it into an inline function. But how do I make it work in my case? warning: friend declaration std::ostream& operator<<(std::ostream&, const D<classT>&)' declares a non-template function warning: (if this is not what you intended, make sure the function template has already been declared and add <> after

问题 Please can you tell me if it is possible to overload operators in Java? If it is used anywhere in Java could you please tell me about it. 回答1: No, Java doesn't support user-defined operator overloading. The only aspect of Java which comes close to "custom" operator overloading is the handling of + for strings, which either results in compile-time concatenation of constants or execution-time concatenation using StringBuilder/StringBuffer. You can't define your own operators which act in the

问题 I want to add two arrays by simply writing: int a[4] = {1,2,3,4}; int b[4] = {2,1,3,1}; int sum[4] = a + b; I wrote this function but I got an error int* operator+(const uint32& other) const{ uint32 sum[n]; for(int i=0; i<n; i++){ sum[i] = (*this[i]) + other[i]; } return sum; } Could you help me on this? Thanks in advance. 回答1: This is probably wrong, but it appears to work (C++11): #include <iostream> #include <array> using namespace std; template <class T> T operator+(const T& a1, const T&

问题 So I have looked around because this seems to be a common homework problem for most C++ students, but I can't seem to find one that will answer my issue. I feel that I have filled out the code correctly but I get the same error each time. Here is my code: #include <iostream> using namespace std; class Rational { public: Rational() { num = 0; denom = 1; }; Rational(int n, int d) { num = n; denom = d; normalize(); } Rational(int n) { num = n; denom = 1; } int get_numerator() const { return num;

问题 Im having trouble figuring out where to place the overloaded operators i created. should they be in the class they operate on, or inside? both ways are causing me trouble. any pointers would be great. here is my very basic uint128_t class: class uint128_t{ private: uint64_t UPPER, LOWER; public: // constructors uint128_t(){ UPPER = 0; LOWER = 0; } template <typename T> uint128_t(T val){ UPPER = 0; LOWER = (uint64_t) val; } template <typename S, typename T> uint128_t(const S & upper_val, const

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Java String.equals versus == Is it possible to compare Java Strings using == operator? Why do I often see, that equals() method is used instead? Is it because when comparing with literal Strings (like "Hello") using == doesn't imply calling equals()? 回答1: there is no custom operator overloading in java. [so you cannot overload it to call equals()] the equals() ensures you check if 2 Objects are identical,while =