Literacy for Golang Beginners: Clear Answers to Common Problems

Solving common problems for Golang beginners: accessing global variables: Use global_variable syntax, such as global_variable_x. Modify function parameter values: Use reference transfer (pointer), such as *y = 10. Wait for the goroutine to complete: use sync.WaitGroup, such as wg.Wait(). To create a copy of a slice: use make() and copy(), such as c := make([]int, len(a)); copy(c, a).

Golang Beginner’s Guide: Simple Answers to Common Problems

Introduction

Golang, a powerful programming language favored by beginners for its simplicity, concurrency, and garbage collection features. However, novices will inevitably encounter some common problems when writing Golang code. To help them overcome these difficulties, this article explores some common challenges and their clear solutions.

Problem 1: Variable declaration and scope

var x int = 5  // 全局变量
func main() {
    x := 10 // 局部变量
    fmt.Println(x) // 输出局部变量的值
}

Question: Local variables and global variables have the same name, how to access global variables?

Solution: When using global variables, you need to use global_variable Syntax:

func main() {
    x := 10 // 局部变量
    fmt.Println(x) // 输出局部变量的值
    fmt.Println(global_variable_x) // 输出全局变量的值
}

Problem 2: Passing by value and passing by reference

func changeValue(x int) {
    x = 10 // 只能修改 x 的局部副本
}

func changeRef(y *int) {
    *y = 10 // 修改指针指向的变量
}

Question: How to modify the value of a function parameter so that the modified value can be accessed outside the function?

Solution: To modify the value of the function parameter, use reference passing, that is, use a pointer:

func changeRef(y *int) {
    *y = 10 // 修改指针指向的变量
    fmt.Println(*y) // 输出修改后的值
}

Problem 3: goroutine and concurrency

func main() {
    wg := new(sync.WaitGroup)
    wg.Add(2)
    go func() {
        fmt.Println("goroutine 1")
        wg.Done()
    }()
    go func() {
        fmt.Println("goroutine 2")
        wg.Done() 
    }()
    wg.Wait()
}

Question: How to ensure that goroutine completes execution before exiting the main() function?

Solution: Use sync.WaitGroup to wait for the goroutine to complete:

func main() {
    wg := new(sync.WaitGroup)
    wg.Add(2)
    go func() {
        fmt.Println("goroutine 1")
        wg.Done()
    }()
    go func() {
        fmt.Println("goroutine 2")
        wg.Done()
    }()
    wg.Wait()  // 等待所有 goroutine 完成
}

Problem 4: Slice and Array

a := []int{1, 2, 3}
b := a  // 引用传递，指向 a 的底层数组

b = append(b, 4)  // 修改 b 将影响 a

c := make([]int, len(a))
copy(c, a)  // 值传递，创建新的底层数组

Question: How to create a copy of a slice so that modifications will not affect the original slice?

Solution: Use the built-in functions make() and copy() to create a copy of the slice to obtain an independent underlying array:

c := make([]int, len(a))
copy(c, a)

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