doublecolon
时间: 2023-12-17 11:02:08 浏览: 23
The double colon (::) is an operator used in object-oriented programming languages like Java and C++ to access methods or variables of a class. It is used to separate the name of a class or namespace from the name of a method or variable within that class or namespace.
For example, in Java, if we have a class called "Person" with a method called "getName", we can access the method using the double colon operator like this:
```
Person p = new Person();
String name = p::getName();
```
In this example, we are creating a new instance of the Person class, and then using the double colon operator to access the getName method of that instance. The resulting string is stored in the "name" variable.
Similarly, in C++, if we have a namespace called "math" with a function called "sqrt", we can access the function using the double colon operator like this:
```
double x = 16.0;
double root = math::sqrt(x);
```
In this example, we are using the double colon operator to access the sqrt function within the math namespace, and passing it the value of x. The resulting square root is stored in the "root" variable.