Master the flow control statement skills in Golang

Flow control statements in Golang are used to control the code execution flow, including basic statements (if else, switch, for) and advanced statements (break, continue, defer). These statements can be used to execute blocks of code based on conditions (if else), select multiple blocks of code to execute (switch), execute code repeatedly (for), exit or skip loops (break/continue), and execute code before the function returns ( defer).

Master the skills of flow control statements in Golang

In Golang, flow control statements determine the sequence flow of program execution. Understanding the usage of these statements is crucial to writing efficient and readable code.

Basic flow control statements

• if else: is used to execute a code block based on conditions.

  if condition {
      // 如果条件为 true，执行此代码块
  } else {
      // 如果条件为 false，执行此代码块
  }

• switch: Select between multiple code blocks based on an expression.

  switch condition {
  case value1:
      // 如果条件等于 value1，执行此代码块
  case value2:
      // 如果条件等于 value2，执行此代码块
  default:
      // 如果条件不等于任何给定值，执行此代码块
  }

• for: is used to repeatedly execute a piece of code until a condition is met.

  for condition {
      // 重复执行此代码块直至条件为 false
  }

Advanced flow control statements

• break: Exit from a loop or switch statement.

  for {
      if condition {
          break // 跳出循环
      }
  }

• continue: Skips the current iteration of the loop and continues with the next iteration.

  for {
      if condition {
          continue // 跳过本次迭代
      }
  }

• #defer: Execute a block of code before the function returns.

  func cleanup() {
      // 清理代码
  }
  
  func main() {
      defer cleanup() // 在函数返回前执行 cleanup()
  }

Practical case

Use switch statement to parse HTTP status code:

import "net/http"

func handleStatusCode(w http.ResponseWriter, r *http.Request) {
    switch r.StatusCode {
    case http.StatusOK:
        w.WriteHeader(http.StatusOK)
        w.Write([]byte("OK"))
    case http.StatusNotFound:
        w.WriteHeader(http.StatusNotFound)
        w.Write([]byte("Not Found"))
    default:
        w.WriteHeader(http.StatusInternalServerError)
        w.Write([]byte("Internal Server Error"))
    }
}

Use break statement to exit the loop ：

func findIndex(arr []int, value int) int {
    for i, v := range arr {
        if v == value {
            return i // 找到值后跳出循环
        }
    }
    return -1 // 未找到值，返回 -1
}

By understanding and mastering the flow control statements in Golang, you can write more powerful and complex programs to meet various needs.

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