golang can be modified

Golang can be modified: Explore the variability of Golang

Golang (also known as Go) is a programming language that has become increasingly popular in recent years. The main design goal of Golang is to improve development efficiency and code readability while maintaining high performance and reliability. Compared with other languages, Golang has a unique design and handling of data variability. This article will explore the variability of Golang, and based on this, explore some basic design ideas of Golang and some problems you may encounter.

In Golang, data types are divided into value types and reference types. Value types include integers, floating point numbers, Boolean values, etc., and their values ​​are stored in stack memory. Reference types include slices, structures, functions, etc. Their values ​​are stored in heap memory and referenced on the stack through pointers.

First, let’s take a look at the variability of value types. In Golang, value types can be changed, but this change will only occur within the current scope. For example:

package main

import "fmt"

func main() {
    i := 1
    fmt.Println(i) // 输出 1

    modify(i)
    fmt.Println(i) // 仍然输出 1
}

func modify(i int) {
    i = 2
}

In this example, we see that modifying the value of i in the modify function will only affect the inside of the modify function variables without affecting the i in the main function. This is because the value type will be copied when the function is called, and only the copied value is modified inside the function.

In contrast, a reference type is passed a reference when a function is called, which is a pointer to a memory address. Therefore, modifications to a reference type within a function will affect the value stored in the address pointed to by the reference type. For example:

package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

func main() {
    p := Person{"Tom", 18}
    fmt.Println(p) // 输出 {Tom 18}

    modify(&p)
    fmt.Println(p) // 输出 {Jerry 20}
}

func modify(p *Person) {
    p.Name = "Jerry"
    p.Age = 20
}

In this example, we define a Person structure and instantiate it in the main function. Then, we pass the pointer of this structure to the modify function, and modify the value of this structure instance in the modify function. As you can see, the structure printed in the main function has been modified to {Jerry 20}.

But the relationship between value types and reference types is sometimes not that simple. For example, there is a type called string in Golang, which is actually a read-only reference type. In other words, for a string variable, we cannot directly modify its internal value. For example:

package main

import "fmt"

func main() {
    s := "hello"
    fmt.Println(s) // 输出 hello

    modify(s)
    fmt.Println(s) // 仍然输出 hello
}

func modify(s string) {
    s = "world"
}

In this example, we tried to modify the value of type string in the modify function, but it did not take effect. This is because the string type is read-only and will be copied when the function is called, so any modifications to the parameters will not affect the original string variable. If we want to modify the value of type string, we need to convert it to a writable []byte type, for example:

package main

import "fmt"

func main() {
    s := "hello"
    fmt.Println(s) // 输出 hello

    modify(&s)
    fmt.Println(s) // 输出 world
}

func modify(s *string) {
    b := []byte(*s)
    b[0] = 'w'
    *s = string(b)
}

In this example, we Pass a pointer of type string to the modify function and inside the function convert it to type []byte, then modify the last letter and convert back again stringType. Although this method can achieve string type modification, it increases the complexity of the code.

Golang considers the variability of data when designing and makes corresponding designs. In Golang, try to avoid using global variables and unpredictable function calls. At the same time, Golang's built-in functions are pure functions and will not be modified in any way. These designs make Golang code easier to understand and maintain, while also reducing risks when the code is run.

In summary, modifications to Golang value types will only affect the current scope, while modifications to reference types will change the value stored in the pointed address. When modifying the string type, you need to pay attention to its read-only feature. You can use the []byte type to convert and modify it. Golang's design ideas and processing methods reflect its high emphasis on code readability and reliability. In the development of Golang, we should fully understand its variability characteristics and gradually adapt to its design ideas and processing methods to improve code quality and efficiency.

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