operator-keyword

What is the state of the art about functions to check whether a value is set or not ? For example, the below iterator parses cells. Some cells contain a value, other cells are empty. What is the most convenient way? struct iterator { //usage: bool isset() const // if (it.isset()) bool isSet() const // if (it.isSet()) bool empty() const // if (it.empty()) bool is_set() const // if (it.is_set()) bool is_valid() const // if (it.is_valid()) operator void*() const; // if (it) explicit operator bool() const; // if ((bool)it) or if(it) //thanks @stijn operator bool() const; // if (it) //why not

I saw <?= and >?= used in a code: http://community.topcoder.com/stat?c=problem_solution&rm=151152&rd=5854&pm=2923&cr=310333 I tried to compile without the includes to test if it's standard, but it didn't work. I then added the includes, but it still gives the same error: question-mark.cpp:15:5: error: expected primary-expression before ‘?’ token question-mark.cpp:15:6: error: expected primary-expression before ‘=’ token question-mark.cpp:15:9: error: expected ‘:’ before ‘;’ token question-mark.cpp:15:9: error: expected primary-expression before ‘;’ token #include <stdio.h> #include <algorithm>

There is an operator ? : in Java which can be used to select a value according to the boolean expression. For example, the expression 3 > 2 ? "true" : false will return a string "true" . I know we can use if expression to do this, but I will prefer this style because it is concise and elegant. In Java, there is a difference between if and ? : and that is that if is a statement while ? : is an expression . In Scala, if is also an expression : it returns a value that you can for example assign to a variable. The if in Scala is much more like ? : in Java than the if in Java: // In Scala 'if'

This question already exists : Closed 7 years ago . Possible Duplicate: accessing a python int literals methods In Python, everything is an object . But then again, why doesn't the following snippet work? 1.__add__(2) However, this does work: n = 1 n.__add__(2) What is the difference between n and 1 ? Isn't it a design failure that it doesn't work? For instance, it does work with string literals as well. "one".__add__("two") For comparison, it works well on other purely object oriented languages too. Let's take a closer look at this compiling c# example: Console.WriteLine(100.ToString()); Then

I am following good programming practices and I am logging the PHP errors to file instead of displaying it to user. I use set_error_handler() for that. Now the problem. For example, I have somewhere: @file_exists('/some/file/that/is/outside/openbasedir.txt'); But despite the error suppression operator, the error message logs. I don't want that. I want suppressed errors not to pass to my error handler. The @ operator temporarily sets error_reporting to 0, so you can test the value of error_reporting in your error handler: if (ini_get('error_reporting') == 0) { return; } Or even better, log only

#include<iostream> using namespace std; class complex { double real; double image; public: complex(double r=0,double i=0) : real(r), image(i) { }; complex(const complex& c) : real(c.real), image(c.image) { }; ~complex(){}; double re() const { return real; }; double im() const{ return image; }; const complex& operator =(const complex&c) { real = c.real; image = c.image; return *this; }; const complex& operator +=(const complex&c) { real += c.real; image += c.image; return *this; }; const complex& operator -=(const complex&c) { real -= c.real; image -= c.image; return *this; }; const complex&

I made a class Array which holds an integer array. From the main function, I'm trying to get an element of the array in Array using [ ] as we do for arrays declared in main. I overloaded the operator [ ] as in the following code; the first function returns an lvalue and the second an rvalue (Constructors and other member functions are not shown.) #include <iostream> using namespace std; class Array { public: int& operator[] (const int index) { return a[index]; } int operator[] (const int index) const { return a[index]; } private: int* a; } However, when I try to call those two functions from

I want to overload the * operator in python. In C++, you can overload the dereference operator, so that you can create a class with a custom way to respond to *alpha . Part of this question is that I don't know exactly, and I mean EXACTLY, what the * operator (unpacking operator as I call it) does. So how can I overload it, or emulate the overloading of it. Eventually I want to be able to do: *alpha with a custom response and return value. EDIT: I found the solution thanks to Joe Kington's comment. As *alpha unpacks according to __iter__ , so I defined a simple class that can be inherited from