constructor

问题 Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . Improve this question I want to create a base class and get an error with my initializer list in default constructor. Here are the errors I'm getting: giasuc.cpp:3:8: error: expected unqualified-id before ')' token GiaSuc(): ten(""), soConSinh(0), soLitSua(0) { ^ giasuc.cpp:6:14:

问题 Does Python have a mechanism for class constructors, i.e. a function that is called whenever the class is first referenced (as opposed to when an instance of that object is created)? I know this exists in some other languages, but I haven't come across it in Python. Basically, I would like to initialise some static attributes in that function. I put an example below of what I would expect. Of course, the example returns None, but I would like it return 'foo'. class T: arg = None def __class

问题 As an example lets say I have a class called File . Now file can be opened as binary or text. My constructor is currently File(const char*filename) . Let's suppose the implementation of open is completely different binary and text. How the heck do I construct this? I thought about using a static function but I don't want to return a pointer. I could pass in a pointer but I rather not allow a class be constructed without actually initializing it. I was thinking about having an enum or bool in

问题 Suppose I have the following simple class: struct employee{ std::string name; short salary; std::size_t age; employee(std::string name, short salary, std::size_t age) : name{name}, salary{salary}, age{age}{} }; Since I want array-like access to the name member of employee in an array of employees, I need for example that the offsets are divisible: static_assert( sizeof(employee) % sizeof(std::string) == 0, "!" ); In order to ensure that I am using the alignas directive: struct alignas(sizeof

问题 Suppose I have the following simple class: struct employee{ std::string name; short salary; std::size_t age; employee(std::string name, short salary, std::size_t age) : name{name}, salary{salary}, age{age}{} }; Since I want array-like access to the name member of employee in an array of employees, I need for example that the offsets are divisible: static_assert( sizeof(employee) % sizeof(std::string) == 0, "!" ); In order to ensure that I am using the alignas directive: struct alignas(sizeof

问题 Suppose I have the following simple class: struct employee{ std::string name; short salary; std::size_t age; employee(std::string name, short salary, std::size_t age) : name{name}, salary{salary}, age{age}{} }; Since I want array-like access to the name member of employee in an array of employees, I need for example that the offsets are divisible: static_assert( sizeof(employee) % sizeof(std::string) == 0, "!" ); In order to ensure that I am using the alignas directive: struct alignas(sizeof

问题 As far as I know, in C#, there is no support for the "friend" key word as in C++. Is there an alternative way to design a class that could achieve this same end result without resorting to the un-available "friend" key-word? For those who don't already know, the Friend key word allows the programmer to specify that a member of class "X" can be accessed and used only by class "Y". But to any other class the member appears private so they cannot be accessed. Class "Y" does not have to inherit

问题 I have two classes, A and B, and B is derived from A. A has multiple constructors (2 in the example below). B has one additional member to initialize (which has a default initializer). How can I achieve that B can be construced using one of the constructors of A without having to manually rewrite all the constructor overloads from A in B? (In the example below, I would otherwise have to provide four constructors for B: B():A(){} , B(string s):A(s){} , B(int b):A(),p(b){} , B(string s, int b)

问题 I have two classes, A and B, and B is derived from A. A has multiple constructors (2 in the example below). B has one additional member to initialize (which has a default initializer). How can I achieve that B can be construced using one of the constructors of A without having to manually rewrite all the constructor overloads from A in B? (In the example below, I would otherwise have to provide four constructors for B: B():A(){} , B(string s):A(s){} , B(int b):A(),p(b){} , B(string s, int b)

问题 I have a class of form something like this: class A{ public function __constructor(classB b , classC c){ // } public function getSum(var1, var2){ return var1+var2; } } My test case class is something like this: use A; class ATest extends PHPUnit_Framework_TestCase{ public function testGetSum{ $a = new A(); $this->assertEquals(3, $a->getSum(1,2)); } } However when I run the phpunit, it throws some error like: Missing argument 1 for \..\::__construct(), called in /../A.php on line 5 Even if I