Go的基本语法
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.vscode/settings.json
vendored
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.vscode/settings.json
vendored
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@ -0,0 +1,5 @@
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{
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"files.associations": {
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"stdio.h": "c"
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}
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}
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@ -32,10 +32,9 @@ func main() {
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}
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```
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- 我们写完了程序，如何把这个程序运行起来呢，分为两步:
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- 第一步：执行指令`go mod init`，初始化与版本相关联的 Go 包的集合，确定了根目录、定义了项目的依赖和版本，确保项目可以重建。（也叫做Go的模块）！这一步，会在当前路径下创建`go.mod`文件
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- 第一步：执行指令`go mod init xxx` ，初始化与版本相关联的 Go 包的集合，确定了根目录、定义了项目的依赖和版本，确保项目可以重建。（也叫做Go的模块）！这一步，会在当前路径下创建`go.mod`文件
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- 第二步：执行指令`go mod tidy`，拉取我们需要的go的组建（又叫做库），这个操作可以类比为`pip install -r requirements.txt`，所需要的包IDE会自动写入`go.mod`文件中。
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- 
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- 随后，通过上面这两步，go程序就初始化好了，相关的包也下载好了，接下来，我们就能重新运行了
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- 运行项目:`go run` 开始执行整个项目
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- 运行单个程序: `go run xxx.go`
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- 运行项目: `go run xxx.go`
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- 构建go项目（将整个项目打包成为可执行文件） `go build`
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@ -0,0 +1,265 @@
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### **1. 基础结构**
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```go
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package main // 包声明（必须）
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import "fmt" // 导入包
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func main() { // 主函数（程序入口）
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fmt.Println("Hello, World!")
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}
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```
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---
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### **2. 变量与常量**
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- **变量声明**
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```go
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var a int = 10 // 显式类型
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var b = 20 // 类型推断
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c := 30 // 短声明（函数内使用）
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var d, e int = 1, 2 // 多变量声明
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```
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- **常量**
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```go
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const Pi = 3.14
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const (
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A = 1
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B = 2
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)
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```
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- 着重强调：**开头是大写的是Public！**
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---
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### **3. 基本数据类型**
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- **基本类型**
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```go
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int, int8, int16, int32, int64
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uint, uint8, uint16, uint32, uint64
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float32, float64
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bool
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string
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byte (等同于 uint8)
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rune (等同于 int32, 表示 Unicode 字符)
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```
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- **复合类型**
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```go
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var arr [3]int // 数组（固定长度）
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slice := []int{1, 2, 3} // 切片（动态数组）
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m := map[string]int{"key": 1} // 映射（字典）
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type Person struct { Name string } // 结构体
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```
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---
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### **4. 控制结构**
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- **条件语句**
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```go
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if x > 0 {
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// ...
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} else if x == 0 {
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// ...
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} else {
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// ...
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}
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```
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- **循环**
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```go
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for i := 0; i < 10; i++ { ... } // 传统 for 循环
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for i < 10 { ... } // 类似 while
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for index, value := range slice { ... } // 遍历切片/数组/map
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```
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- **Switch**
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```go
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switch x {
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case 1:
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// ...
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case 2, 3: // 多值匹配
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// ...
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default:
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// ...
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}
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```
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- 特点:不需要break！
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---
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### **5. 函数**
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- **基本函数**
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```go
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func add(a int, b int) int {
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return a + b
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}
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```
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- **多返回值**
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```go
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func swap(a, b int) (int, int) {
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return b, a
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}
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```
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- **命名返回值**
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```go
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func split(sum int) (x, y int) {
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x = sum * 4 / 9
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y = sum - x
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return // 隐式返回 x, y
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}
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```
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- **匿名函数与闭包**（即函数内套函数）
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```go
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func() {
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fmt.Println("Anonymous function")
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}()
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```
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---
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### **6. 指针与结构体**
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- **指针**
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```go
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var p *int
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x := 10
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p = &x
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*p = 20 // 修改 x 的值
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```
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- 特点:
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- Go 的指针**不支持算术运算**，避免了内存越界和非法访问的风险，同时通过垃圾回收机制自动管理内存，**减少了内存泄漏的可能性**。
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- Go 的指针类型严格区分，空指针用 `nil` 表示，解引用空指针会触发 panic，不支持**指针算术运算和强制类型转换**。
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- **结构体与方法**
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```go
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type Circle struct {
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Radius float64
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}
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// 方法（值接收者）
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func (c Circle) Area() float64 {
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return math.Pi * c.Radius * c.Radius
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}
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// 方法（指针接收者）
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func (c *Circle) Scale(factor float64) {
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c.Radius *= factor
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}
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```
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---
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### **7. 接口与错误处理**
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- **接口**
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```go
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type Shape interface {
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Area() float64
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}
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// 隐式实现接口
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func (c Circle) Area() float64 { ... }
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```
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- **错误处理**
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```go
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func readFile() ([]byte, error) {
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data, err := os.ReadFile("file.txt")
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if err != nil {
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return nil, err
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}
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return data, nil
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}
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// 调用
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data, err := readFile()
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if err != nil {
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log.Fatal(err)
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}
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```
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- **Panic & Recover**
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```go
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func safeCall() {
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defer func() {
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if r := recover(); r != nil {
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fmt.Println("Recovered:", r)
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}
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}()
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panic("Something went wrong!")
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}
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```
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---
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### **8. 并发编程**
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- **Goroutine**
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```go
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go func() {
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fmt.Println("Running in goroutine")
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}()
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```
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- **Channel**（数据通道）
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```go
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ch := make(chan int)
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go func() { ch <- 1 }() // 发送数据
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value := <-ch // 接收数据
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```
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- **Select**（主要用于事件驱动）
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```go
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select {
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case msg1 := <-ch1:
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fmt.Println(msg1)
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case msg2 := <-ch2:
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fmt.Println(msg2)
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case <-time.After(1 * time.Second):
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fmt.Println("Timeout")
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}
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```
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---
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### **9. 包与模块**
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- **创建模块**
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```bash
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go mod init xx
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```
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- **导入包**
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```go
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import (
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"fmt"
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"math/rand"
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"github.com/user/package"
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)
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```
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---
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### **10. 其他特性**
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- **Defer**
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- `defer` 是 Go 语言中的一个关键字，用于延迟执行一个函数调用。**被 `defer` 修饰的函数调用会推迟到当前函数返回之前执行**，无论当前函数是正常返回还是由于错误（如 `panic`）提前返回。`defer` 的主要用途是确保某些操作（如资源释放、清理工作等）一定会被执行，避免遗漏。
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```go
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func readFile() {
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file, _ := os.Open("file.txt")
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defer file.Close() // 函数返回前执行
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// ...
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}
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```
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- **JSON 处理**
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```go
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type User struct {
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Name string `json:"name"`
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Age int `json:"age"`
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}
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data, _ := json.Marshal(user) //序列化
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```
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---
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### **常用内置函数**
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- `len()`：获取长度
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- `cap()`：切片容量
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- `make()`：创建切片/map/channel
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- `append()`：切片追加元素
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BIN
Go入门速成/Day1/ExampleCode/BasicGrammar/BasicGrammar
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BIN
Go入门速成/Day1/ExampleCode/BasicGrammar/BasicGrammar
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Go入门速成/Day1/ExampleCode/BasicGrammar/PointerPanic.go
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1
Go入门速成/Day1/ExampleCode/BasicGrammar/PointerPanic.go
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package main
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3
Go入门速成/Day1/ExampleCode/BasicGrammar/go.mod
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3
Go入门速成/Day1/ExampleCode/BasicGrammar/go.mod
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module BasicGrammar
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go 1.24.1
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147
Go入门速成/Day1/ExampleCode/BasicGrammar/main.go
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147
Go入门速成/Day1/ExampleCode/BasicGrammar/main.go
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package main
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import (
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"errors"
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"fmt"
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"sync"
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"time"
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)
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// 常量
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const Pi = 3.14159
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// 结构体
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type Circle struct {
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Radius float64
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}
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// 方法（值接收者）
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func (c Circle) Area() float64 {
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return Pi * c.Radius * c.Radius
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}
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// 方法（指针接收者）
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func (c *Circle) Scale(factor float64) {
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c.Radius *= factor
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}
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// 接口
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type Shape interface {
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Area() float64
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}
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// 函数（多返回值）
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func divide(a, b float64) (float64, error) {
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if b == 0 {
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return 0, errors.New("division by zero")
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}
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return a / b, nil
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}
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// 主函数
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func main() {
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// 变量声明
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var a int = 10
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b := 20
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c, d := 30, 40
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fmt.Println("Variables:", a, b, c, d)
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// 数组与切片
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arr := [3]int{1, 2, 3}
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slice := []int{4, 5, 6}
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slice = append(slice, 7)
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fmt.Println("Array:", arr, "Slice:", slice)
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// 映射
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m := map[string]int{"one": 1, "two": 2}
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fmt.Println("Map:", m)
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// 控制结构
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if a > 5 {
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fmt.Println("a is greater than 5")
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} else {
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fmt.Println("a is not greater than 5")
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}
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for i := 0; i < 3; i++ {
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fmt.Println("Loop:", i)
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}
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switch a {
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case 10:
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fmt.Println("a is 10")
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default:
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fmt.Println("a is not 10")
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}
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// 函数调用
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result, err := divide(10, 2)
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if err != nil {
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fmt.Println("Error:", err)
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} else {
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fmt.Println("Division result:", result)
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}
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// 指针
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x := 10
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p := &x
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*p = 20
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fmt.Println("Pointer:", x)
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// 结构体与方法
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circle := Circle{Radius: 5}
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fmt.Println("Circle area:", circle.Area())
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circle.Scale(2)
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fmt.Println("Scaled circle area:", circle.Area())
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// 接口
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var shape Shape = Circle{Radius: 3}
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fmt.Println("Shape area:", shape.Area())
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// 错误处理
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_, err = divide(10, 0)
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if err != nil {
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fmt.Println("Error:", err)
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}
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// 并发
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var wg sync.WaitGroup
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wg.Add(1)
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go func() {
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defer wg.Done()
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fmt.Println("Running in goroutine")
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}()
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wg.Wait()
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|
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// Channel
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ch := make(chan int)
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go func() {
|
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ch <- 42
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}()
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value := <-ch
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fmt.Println("Channel value:", value)
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|
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// Select
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ch1 := make(chan string)
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ch2 := make(chan string)
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go func() {
|
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time.Sleep(1 * time.Second)
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ch1 <- "from ch1"
|
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}()
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go func() {
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time.Sleep(2 * time.Second)
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ch2 <- "from ch2"
|
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}()
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select {
|
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case msg := <-ch1:
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fmt.Println("Select:", msg)
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case msg := <-ch2:
|
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fmt.Println("Select:", msg)
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case <-time.After(3 * time.Second):
|
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fmt.Println("Timeout")
|
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}
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|
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// Defer
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defer fmt.Println("Defer: This runs last")
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fmt.Println("Main function end")
|
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}
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21
Go入门速成/Day1/ExampleCode/BasicGrammar/switch.c
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21
Go入门速成/Day1/ExampleCode/BasicGrammar/switch.c
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//go:build ignore
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// +build ignore
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|
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|
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#include "stdio.h"
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|
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int main() {
|
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int a = 2;
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switch (a) {
|
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case 1:
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printf("a = 1\n");
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break;
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case 2:
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printf("a = 2\n");
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break;
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case 3:
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printf("a = 3\n");
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break;
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default:
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printf("FUCK"); // default 语句是可选的
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}
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31
Go入门速成/Day2/Class3 Gorm的使用.md
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31
Go入门速成/Day2/Class3 Gorm的使用.md
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# Gorm的使用
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## Gorm是什么
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- GORM 是 Go 语言的 ORM 库，提供模型定义、关联管理、事务支持、查询构建、数据迁移、钩子回调等功能，支持主流数据库（如 MySQL/PostgreSQL/SQLite），简化数据库操作。
|
||||
## 如何使用Gorm
|
||||
### 导入Gorm库
|
||||
```go
|
||||
import (
|
||||
"gorm.io/driver/mysql"
|
||||
)
|
||||
```
|
||||
### 基本操作
|
||||
- 1、连接数据库
|
||||
```go
|
||||
const (
|
||||
USERNAME = "root"
|
||||
PASSWD = "oppofindx2"
|
||||
DATABASENAME = "Class"
|
||||
)
|
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dsn := fmt.Sprintf("%s:%s@tcp(127.0.0.1:3306)/%s?charset=utf8mb4&parseTime=True&loc=Local", USERNAME, PASSWD, DATABASENAME)
|
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db := mysql.Open(dsn)
|
||||
`````
|
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- 2、数据库中表的定义
|
||||
- 在Gorm中，定义一张表使用的是结构体
|
||||
```go
|
||||
type User struct {
|
||||
gorm.Model
|
||||
Name string
|
||||
Age int
|
||||
}
|
||||
```
|
||||
- 自动迁移表结构（方便我们修改表，给表添加参数）
|
||||
12
Go入门速成/Day2/ExampleCode/Gorm/go.mod
Normal file
12
Go入门速成/Day2/ExampleCode/Gorm/go.mod
Normal file
@ -0,0 +1,12 @@
|
||||
module Gorm
|
||||
|
||||
go 1.24.1
|
||||
|
||||
require gorm.io/driver/mysql v1.5.7
|
||||
|
||||
require (
|
||||
github.com/go-sql-driver/mysql v1.7.0 // indirect
|
||||
github.com/jinzhu/inflection v1.0.0 // indirect
|
||||
github.com/jinzhu/now v1.1.5 // indirect
|
||||
gorm.io/gorm v1.25.7 // indirect
|
||||
)
|
||||
10
Go入门速成/Day2/ExampleCode/Gorm/go.sum
Normal file
10
Go入门速成/Day2/ExampleCode/Gorm/go.sum
Normal file
@ -0,0 +1,10 @@
|
||||
github.com/go-sql-driver/mysql v1.7.0 h1:ueSltNNllEqE3qcWBTD0iQd3IpL/6U+mJxLkazJ7YPc=
|
||||
github.com/go-sql-driver/mysql v1.7.0/go.mod h1:OXbVy3sEdcQ2Doequ6Z5BW6fXNQTmx+9S1MCJN5yJMI=
|
||||
github.com/jinzhu/inflection v1.0.0 h1:K317FqzuhWc8YvSVlFMCCUb36O/S9MCKRDI7QkRKD/E=
|
||||
github.com/jinzhu/inflection v1.0.0/go.mod h1:h+uFLlag+Qp1Va5pdKtLDYj+kHp5pxUVkryuEj+Srlc=
|
||||
github.com/jinzhu/now v1.1.5 h1:/o9tlHleP7gOFmsnYNz3RGnqzefHA47wQpKrrdTIwXQ=
|
||||
github.com/jinzhu/now v1.1.5/go.mod h1:d3SSVoowX0Lcu0IBviAWJpolVfI5UJVZZ7cO71lE/z8=
|
||||
gorm.io/driver/mysql v1.5.7 h1:MndhOPYOfEp2rHKgkZIhJ16eVUIRf2HmzgoPmh7FCWo=
|
||||
gorm.io/driver/mysql v1.5.7/go.mod h1:sEtPWMiqiN1N1cMXoXmBbd8C6/l+TESwriotuRRpkDM=
|
||||
gorm.io/gorm v1.25.7 h1:VsD6acwRjz2zFxGO50gPO6AkNs7KKnvfzUjHQhZDz/A=
|
||||
gorm.io/gorm v1.25.7/go.mod h1:hbnx/Oo0ChWMn1BIhpy1oYozzpM15i4YPuHDmfYtwg8=
|
||||
27
Go入门速成/Day2/ExampleCode/Gorm/main.go
Normal file
27
Go入门速成/Day2/ExampleCode/Gorm/main.go
Normal file
@ -0,0 +1,27 @@
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
|
||||
"gorm.io/driver/mysql"
|
||||
"gorm.io/gorm"
|
||||
)
|
||||
|
||||
const (
|
||||
USERNAME = "root"
|
||||
PASSWD = "oppofindx2"
|
||||
DATABASENAME = "Class"
|
||||
)
|
||||
|
||||
func main() {
|
||||
ls
|
||||
dsn := fmt.Sprintf("%s:%s@tcp(127.0.0.1:3306)/%s?charset=utf8mb4&parseTime=True&loc=Local", USERNAME, PASSWD, DATABASENAME)
|
||||
db := mysql.Open(dsn)
|
||||
print(db)
|
||||
}
|
||||
|
||||
type User struct {
|
||||
gorm.Model
|
||||
Name string
|
||||
Age int
|
||||
}
|
||||
Loading…
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Reference in New Issue
Block a user