This article will introduce how to use Go language to implement a simple and easy-to-understand order system.
1. Demand Analysis
We need a simple and easy-to-understand ordering system, which at least needs to implement the following functions:
Considering that our time and energy are limited, we will only implement a simple mall system, and we Only two items are available to choose from. The information of these two products is as follows:
| Product name | Product price |
|---|---|
| Product 1 | 10 yuan |
| Product 2 | 20 yuan |
We need Implement this mall system in the command line.
2. Code implementation
We first need to create a structure to store product information. The code example is as follows:
type product struct {
name string
price int
}
var products = []product{
{"商品1", 10},
{"商品2", 20},
}We need to implement a function to display product information. The code example is as follows:
func showProducts() {
fmt.Println("== 商品列表 ==")
for _, p := range products {
fmt.Printf("%s %d元\n", p.name, p.price)
}
fmt.Println("================")
}We need to implement a shopping cart structure to store the product information selected by the user. The code example is as follows:
type cart struct {
items map[string]int
}
func newCart() *cart {
return &cart{items: make(map[string]int)}
}
func (c *cart) addItem(name string, qty int) {
c.items[name] += qty
}
func (c *cart) clear() {
c.items = make(map[string]int)
}
func (c *cart) total() int {
total := 0
for name, qty := range c.items {
for _, p := range products {
if p.name == name {
total += p.price * qty
break
}
}
}
return total
}
func (c *cart) show() {
if len(c.items) == 0 {
fmt.Println("购物车为空")
return
}
fmt.Println("== 购物车 ==")
for name, qty := range c.items {
fmt.Printf("%s × %d\n", name, qty)
}
fmt.Printf("总计 %d元\n", c.total())
fmt.Println("============")
}We need to implement An order function is to generate the product information in the shopping cart into an order. The code example is as follows:
func checkout(c *cart) {
if len(c.items) == 0 {
fmt.Println("购物车为空")
return
}
// 生成订单
order := make(map[string]int)
for name, qty := range c.items {
order[name] = qty
}
// 清空购物车
c.clear()
fmt.Println("== 订单详情 ==")
for name, qty := range order {
for _, p := range products {
if p.name == name {
fmt.Printf("%s × %d\n", name, qty)
fmt.Printf("单价 %d元，总价 %d元\n", p.price, p.price*qty)
break
}
}
}
fmt.Printf("总计 %d元\n", c.total())
fmt.Println("============")
}We need to implement a command line interaction function , for users to select the product and quantity, and complete the order. The code example is as follows:
func interactive() {
scanner := bufio.NewScanner(os.Stdin)
c := newCart()
for {
showProducts()
c.show()
fmt.Print("请选择商品（输入商品编号）：")
scanner.Scan()
id := scanner.Text()
if id == "q" {
break
}
var p product
for _, p = range products {
if p.name == id {
break
}
}
if p.price == 0 {
fmt.Printf("商品 %s 不存在\n", id)
continue
}
fmt.Print("请输入数量：")
scanner.Scan()
qtyStr := scanner.Text()
qty, err := strconv.Atoi(qtyStr)
if err != nil {
fmt.Println("输入的数量无效")
continue
}
c.addItem(p.name, qty)
}
checkout(c)
}3. The complete code
The complete code is as follows:
package main
import (
"bufio"
"fmt"
"os"
"strconv"
)
type product struct {
name string
price int
}
var products = []product{
{"商品1", 10},
{"商品2", 20},
}
type cart struct {
items map[string]int
}
func newCart() *cart {
return &cart{items: make(map[string]int)}
}
func (c *cart) addItem(name string, qty int) {
c.items[name] += qty
}
func (c *cart) clear() {
c.items = make(map[string]int)
}
func (c *cart) total() int {
total := 0
for name, qty := range c.items {
for _, p := range products {
if p.name == name {
total += p.price * qty
break
}
}
}
return total
}
func (c *cart) show() {
if len(c.items) == 0 {
fmt.Println("购物车为空")
return
}
fmt.Println("== 购物车 ==")
for name, qty := range c.items {
fmt.Printf("%s × %d\n", name, qty)
}
fmt.Printf("总计 %d元\n", c.total())
fmt.Println("============")
}
func showProducts() {
fmt.Println("== 商品列表 ==")
for _, p := range products {
fmt.Printf("%s %d元\n", p.name, p.price)
}
fmt.Println("================")
}
func checkout(c *cart) {
if len(c.items) == 0 {
fmt.Println("购物车为空")
return
}
// 生成订单
order := make(map[string]int)
for name, qty := range c.items {
order[name] = qty
}
// 清空购物车
c.clear()
fmt.Println("== 订单详情 ==")
for name, qty := range order {
for _, p := range products {
if p.name == name {
fmt.Printf("%s × %d\n", name, qty)
fmt.Printf("单价 %d元，总价 %d元\n", p.price, p.price*qty)
break
}
}
}
fmt.Printf("总计 %d元\n", c.total())
fmt.Println("============")
}
func interactive() {
scanner := bufio.NewScanner(os.Stdin)
c := newCart()
for {
showProducts()
c.show()
fmt.Print("请选择商品（输入商品编号）：")
scanner.Scan()
id := scanner.Text()
if id == "q" {
break
}
var p product
for _, p = range products {
if p.name == id {
break
}
}
if p.price == 0 {
fmt.Printf("商品 %s 不存在\n", id)
continue
}
fmt.Print("请输入数量：")
scanner.Scan()
qtyStr := scanner.Text()
qty, err := strconv.Atoi(qtyStr)
if err != nil {
fmt.Println("输入的数量无效")
continue
}
c.addItem(p.name, qty)
}
checkout(c)
}
func main() {
interactive()
}4. Summary
This article briefly introduces how to use Go language to implement a simple and easy-to-understand ordering system. By implementing functions such as product display, shopping cart function, and order generation and display, we have implemented a useful mall system with certain functions. Practicality and reference value. Before development, we need to fully understand the needs and goals so that we can better complete product development. At the same time, the efficiency and simplicity of the Go language also provide us with reliable and efficient development tools and support.
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