operator-keyword

问题 I have trouble understanding what happens when calling &*pointer int j=8; int* p = &j; When I print in my compiler I get the following j = 8 , &j = 00EBFEAC p = 00EBFEAC , *p = 8 , &p = 00EBFEA0 &*p= 00EBFEAC cout << &*p gives &*p = 00EBFEAC which is p itself & and * have same operator precedence.I thought &*p would translate to &(*p)--> &(8) and expected compiler error. How does compiler deduce this result? 回答1: You are stumbling over something interesting: Variables, strictly spoken, are

问题 I checked the operator precedence in Python 3(https://docs.python.org/3/reference/expressions.html#operator-precedence), and found that there is no assignment(=). I want to know if assignment is an operator or not. If not, why there are so many "assignment operator" info when googled? What is the precedence relation with other real operators(bool operator, comparison operator, etc)? 回答1: No. An assignment is always a statement in Python. That's why things like assignment within if statements,

问题 I have a test class of my to make my own string functions. I have a problem with the copy destructor. I have 2 strings: s1 and s2. I call the function s3 = s1 + s2; It first calls the operator+ function and when it's finished it calls the destructor. Because of this the string object in the operator= function is empty. How can I fix this? Destructor: String::~String() { if (this->str) delete[] str; str = NULL; len = 0; } Copy Constructor: String::String(const String& string) { this->len =

问题 I'm a bit confused. The PHP documenation says: // Example usage for: Null Coalesce Operator $action = $_POST['action'] ?? 'default'; // The above is identical to this if/else statement if (isset($_POST['action'])) { $action = $_POST['action']; } else { $action = 'default'; } But my own example says something very different: echo "<pre>"; $array['intValue'] = time(); $array['stringValue'] = 'Hello world!'; $array['boolValue'] = false; $resultInt = isset($array['intValue']) ?? -1; $resultString

问题 I'm doing a pretty simple project for a class and just wondering if I'm going about it in the right way. We are making a clone of the Windows calculator. For each of the math operators my code is as follows: Private Sub btnPlus_Click(sender As Object, e As EventArgs) Handles btnPlus.Click If opPressed = True Then Select Case (opType) Case "+" txtField.Text = CStr(CDbl(opStore) + CDbl(txtField.Text)) Case "-" txtField.Text = CStr(CDbl(opStore) - CDbl(txtField.Text)) Case "*" txtField.Text =

问题 I'm doing a pretty simple project for a class and just wondering if I'm going about it in the right way. We are making a clone of the Windows calculator. For each of the math operators my code is as follows: Private Sub btnPlus_Click(sender As Object, e As EventArgs) Handles btnPlus.Click If opPressed = True Then Select Case (opType) Case "+" txtField.Text = CStr(CDbl(opStore) + CDbl(txtField.Text)) Case "-" txtField.Text = CStr(CDbl(opStore) - CDbl(txtField.Text)) Case "*" txtField.Text =

问题 I have the code: class Point3D{ protected: float x; float y; float z; public: Point3D(){x=0; y=0; z=0;} Point3D(const Point3D & point){x = point.x; y = point.y; z = point.z;} Point3D(float _x,float _y,float _z){x = _x; y = _y; z = _z;} } class Vector3D{ protected: Point3D start; Point3D end; public: ... Point3D getSizes(){ return Point3D(end-start); } } I want to create and operator+ for Point3D that will take an vector: Point3D & operator+(const Vector3D &vector){ Point3D temp; temp.x = x +

问题 I really don't know how to create this properly. I have templates class with overloads for operators. And as i know i need to create templates to overload this operators for more universal form. My problem is that code not compile and i don't know how to fix it Example: NSize<30> a(101); NSize<25> b(120); NSize<30> c(115); NSize<30> res = (a*b)*(a*c)*(c*b)*(b*a)*(a*c); In the end, I should be able to do it. For now i defined it as : template <int length> friend NSize operator * (const NSize

问题 (Edited version) I am currently coding Binary Search Tree algorithm. (using xCode IDE) I'm taking the data from txt file and insert it as binarysearchtree. This is the sample of data from txt file. 3800 Lee, Victor; 2.8 3000 Brown, Joanne; 4.0 As you can see in student.h, there are 2 variables which are id and student. Id contains the data "3800" and student contains "Lee, Victor; 2.8". Each line of the txt consider as one root. Now, I have to search by a unique key which is id(Ex. "3800")

问题 I have a class, defined in a head as: template <typename T> class MyClass { template <typename U> friend std::ostream& operator<<(std::ostream& output, const MyClass<U>& p); public: ... } In an implementation file, I have: template <typename U> std::ostream& operator<<(std::ostream& output, const MyClass<U>& m) { output << "Some stuff"; return output; } Which all looks fairly kosher. However, when I try and use this operator (i.e. std::cout << MyClass()), I get the following linker error: