Project examples based on golang custom functions

Custom functions allow extending functionality in Go applications. To create a custom function, use the func keyword and declare its name, parameters, and return type. To register a function for use, use http.HandleFunc to intercept the URL path and call the function. This tutorial demonstrates an example of a custom function that calculates the square of a given number, which can be used by sending a GET request to the /square URL path containing the query parameter x.

Project example based on Go language custom function implementation

Introduction

Custom functions allow you to extend the functionality of your Go application. This tutorial will guide you through a practical example of how to create and use custom functions.

Create a custom function

Use the func keyword to create a custom function. Function names, parameters, and return types must be declared as valid types.

// 返回给定数字的平方
func square(x int) int {
  return x * x
}

Register a custom function

To use a custom function, you must register it in your application. Use http.HandleFunc to intercept a specific URL path and call a function.

package main

import (
  "net/http"
)

func main() {
  // 注册 square 函数来处理 "/square" URL 路径
  http.HandleFunc("/square", squareHandler)

  // 启动 HTTP 服务器
  http.ListenAndServe(":8080", nil)
}

func squareHandler(w http.ResponseWriter, r *http.Request) {
  x := r.URL.Query().Get("x")
  result, err := strconv.Atoi(x)
  if err != nil {
    w.Write([]byte("Invalid input"))
    return
  }
  w.Write([]byte(strconv.Itoa(square(result))))
}

Practical case

In this example, the custom function square is used to calculate the square of a given number.

To use this function, send a GET request to the "/square" URL path, including a query parameter named "x" that specifies the number whose square is to be calculated.

For example, enter the following URL into your browser:

http://localhost:8080/square?x=5

This will return the response:

25

Note:

Make sure Your custom function will not have side effects, such as modifying global variables or the file system. This ensures the security and consistency of your application.

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