operator-keyword

问题 So, I just want to know if its possible to slip in any code or a ternary operator inside the termination bit of a for loop. If it is possible, could you provide an example of a ternary operator in a for loop? Thanks! for (initialization; termination; increment) { statement(s) } 回答1: The termination clause in the for statement (if supplied - it's actually optional) can be any expression you want so long as it evaluates to a boolean . It must be an expression , not an arbitrary code block. 回答2:

问题 struct reserved_memory { void *safety; size_t safety_size; reserved_memory(size_t size) : safety_size(size) { init(); } bool use() { if (safety) { ::operator(safety); safety=0; return true; } else return false; } private: void init() { safety=::operator new(safety_size); } } I have this code that isn't compiling - and I also have never seen this before. Is this calling the constructor? There is no overloaded () operator in the struct... 回答1: Seems pretty obvious that whoever wrote that code

问题 //using namespace std; using std::ifstream; using std::ofstream; using std::cout; class Dog { friend ostream& operator<< (ostream&, const Dog&); public: char* name; char* breed; char* gender; Dog(); ~Dog(); }; im trying to overload the << operator. I'm also trying to practice good coding. But my code wont compile unless i uncomment the using namespace std. i keep getting this error and i dont know. im using g++ compiler. Dog.h:20: error: ISO C++ forbids declaration of ‘ostream’ with no type

问题 How it possible to use operator<< to push string s into a vector . I searched a lot but only find stream examples. class CStringData { vector< string > myData; // ... // inline operator << ... ??? }; I want this to use as a simple elipsis (like void AddData(...) ) exchange for robust parameters. CStringData abc; abc << "Hello" << "World"; Is this possible at all ? 回答1: You can define operator<< as: class CStringData { vector< string > myData; public: CStringData & operator<<(std::string const

问题 I have some familiarity with bitwise operations, but this function just went over my head. void binary_print(unsigned int value) { unsigned int mask = 0xff000000; // Start with a mask for the highest byte. unsigned int shift = 256*256*256; // Start with a shift for the highest byte. unsigned int byte, byte_iterator, bit_iterator; for (byte_iterator=0; byte_iterator < 4; byte_iterator++) { byte = (value & mask) / shift; // Isolate each byte. printf(" "); for (bit_iterator=0; bit_iterator < 8;

问题 I have a function and that function takes in a class pointer. the problem is that I call the class pointer like this. Function (new ChildClass); the function looks something like this void Function (BaseClass *instance) { childClassInstance = instance; } the reason why I call it with the new keyword is because I need it outside my function. What I wanted to know was. When I'm ready to delete instance. How would I go about it? Since it's in the function parameter, how would I go about calling

问题 I'm writting a log class in c++. This class is an singleton. I want to add logs in such a way: Log::GetInstance() << "Error: " << err_code << ", in class foo"; Ok, and inside a Log object, I want to save this whole line at the time when the last argument comes (", in class foo" in this example). How to detect the last one << argument? << a << b << is_this_last << maybe_this_is << or_not. I dont to use any end tags. 回答1: You can solve this problem by not using a singleton. If you make a

问题 Some compiler books / articles / papers talk about design of a grammar and the relation of its operator's associativity. I'm a big fan of top-down, especially recursive descent, parsers and so far most (if not all) compilers I've written use the following expression grammar: Expr ::= Term { ( "+" | "-" ) Term } Term ::= Factor { ( "*" | "/" ) Factor } Factor ::= INTEGER | "(" Expr ")" which is an EBNF representation of this BNF: Expr ::= Term Expr' Expr' ::= ( "+" | "-" ) Term Expr' | ε Term

问题 I am trying to implement a simple comparator for sorting indices based on values in an array "_vec". I am getting an "invalid < operator" run-time error message. I fail to understand what is wrong with the following code: class Compare{ vector<int>& _vec; public: Compare(vector<int>& vec) : _vec(vec) {} bool operator()(size_t i, size_t j){ if(_vec[i] != _vec[j]) return _vec[i] < _vec[j]; else return (double)rand()/RAND_MAX < 0.5; } }; I am using the following function call: sort(inds.begin()

问题 I am trying to implement overloading for division operator in python. class Fraction: def __init__(self,top,bottom): def gcd(m, n): while m % n != 0: old_m = m old_n = n m = old_n n = old_m % old_n return n common = gcd(top,bottom) self.num = top/common self.den = bottom/common def __str__ (self): return str(self.num) + "/" + str(self.den) def get_num(self): return self.num def get_den(self): return self.den def __add__(self, other_fraction): new_num = self.num * other_fraction.den + self.den