golang pointer method

Golang is a very powerful programming language with many features and functions, among which pointer methods are a very important feature. This article will introduce the relevant knowledge of Golang pointer methods.

First of all, what is a pointer? In a program, a variable is a label or name that points to a memory address. A pointer is a value that points to the memory address of a variable. By using pointers, the program can directly manipulate data in memory, which can improve the efficiency of the program.

Pointer methods in Golang can be understood as methods defined on a type, and they can directly operate on the internal data of the type. A pointer method is defined by adding a parameter before the method name to specify the receiver of the method. The receiver can be a pointer type or a non-pointer type.

For example, the following code defines a structure type Person, and a pointer type PersonPtr pointing to the Person type:

type Person struct {
    Name string
    Age  int
}

func (p *Person) SayHello() {
    fmt.Printf("Hi, my name is %s. I am %d years old.
", p.Name, p.Age)
}

func main() {
    person := Person{Name: "Bob", Age: 28}
    personPtr := &person
    personPtr.SayHello()
}

In the above code, the Person type defines a pointer method SayHello. The receiver of this method is the pointer type PersonPtr pointing to the Person type, which can directly operate the Person type data.

In the main function, we instantiate a variable person of type Person, and then get a pointer to person type personPtr by taking the address of the variable. Finally, we call the SayHello method of personPtr to output the result.

Pointer methods can be value receivers or pointer receivers. In the above example, we used a pointer receiver, which is p *Person, which means that the method needs to pass in a pointer to the Person type. If you use a value receiver, i.e. p Person, then this method needs to pass in a value of type Person.

The main difference between value receivers and pointer receivers is the different types of variables they can access. In a value receiver, only a copy of the variable can be accessed, whereas in a pointer receiver, the variable itself can be accessed directly. Therefore, when you need to modify the value of a variable, you usually use a pointer receiver; and when you only need to read the value of a variable, it is more appropriate to use a value receiver.

The following is an example of using a value receiver:

type Rectangle struct {
    Length float64
    Width  float64
}

func (r Rectangle) Area() float64 {
    return r.Length * r.Width
}

func main() {
    rect := Rectangle{Length: 10, Width: 5}
    fmt.Println(rect.Area())
}

In the above example, we define a structure type Rectangle, which has two fields Length and Width, and then we define A value receiver method Area is used to calculate the area of ​​the rectangle. In the main function, we instantiate an object rect of type Rectangle and call its Area method.

In short, Golang's pointer method is a very important function. The pointer method can be used to directly operate the internal data of the type, thereby improving the efficiency of the program. When writing code, you need to choose a value receiver or a pointer receiver according to the actual situation.

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