flyfei

字符串处理（strings/split/join/trim等函数、正则表达式regexp）

1. 语法讲解

Go语言的strings包提供了丰富的字符串操作函数，strconv包处理字符串与基本类型的转换，regexp包提供正则表达式功能。

字符串特点：Go中字符串是不可变的字节序列，使用UTF-8编码。

2. 应用场景

3. 编程实例

场景：用户注册信息验证和处理

package main

import (
    "fmt"
    "regexp"
    "strconv"
    "strings"
    "unicode/utf8"
)

// 验证邮箱格式
func validateEmail(email string) bool {
    pattern := `^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$`
    matched, _ := regexp.MatchString(pattern, email)
    return matched
}

// 验证手机号格式
func validatePhone(phone string) bool {
    pattern := `^1[3-9]\d{9}$`
    matched, _ := regexp.MatchString(pattern, phone)
    return matched
}

// 处理用户输入
func processUserInput(input string) map[string]interface{} {
    result := make(map[string]interface{})
    
    // 清理输入
    cleaned := strings.TrimSpace(input)
    cleaned = strings.ToLower(cleaned)
    
    // 分割字段（模拟"name:age:email"格式）
    fields := strings.Split(cleaned, ":")
    if len(fields) < 3 {
        return nil
    }
    
    result["name"] = fields[0]
    
    // 转换年龄
    age, err := strconv.Atoi(strings.TrimSpace(fields[1]))
    if err != nil || age < 0 || age > 150 {
        result["age"] = "无效年龄"
    } else {
        result["age"] = age
    }
    
    // 验证邮箱
    email := strings.TrimSpace(fields[2])
    if validateEmail(email) {
        result["email"] = email
    } else {
        result["email"] = "邮箱格式错误"
    }
    
    // 统计信息
    result["original_length"] = len(input)
    result["cleaned_length"] = len(cleaned)
    result["rune_count"] = utf8.RuneCountInString(cleaned)
    
    return result
}

func main() {
    // 模拟用户输入
    userInputs := []string{
        "john doe:25:john@example.com",
        "  ALICE SMITH:30:alice@gmail.com  ",
        "bob:invalid:bademail",
        "李四:28:lisi@example.com",
    }
    
    for _, input := range userInputs {
        fmt.Printf("处理输入: '%s'\n", input)
        result := processUserInput(input)
        if result == nil {
            fmt.Println("  错误: 输入格式不正确")
        } else {
            for k, v := range result {
                fmt.Printf("  %s: %v\n", k, v)
            }
        }
        fmt.Println()
    }
    
    // 手机号验证
    phones := []string{"13812345678", "12345678900", "15887654321"}
    for _, phone := range phones {
        valid := validatePhone(phone)
        fmt.Printf("手机号 %s 验证结果: %t\n", phone, valid)
    }
}

4. 其他用法

package main

import (
    "fmt"
    "regexp"
    "strconv"
    "strings"
)

func main() {
    text := "订单号: ORD-2023-001, 价格: ￥150.75, 数量: 5, 总计: ￥753.75"
    
    // 使用正则表达式提取信息
    // 提取订单号
    orderPattern := `ORD-\d{4}-\d{3}`
    orderRegex := regexp.MustCompile(orderPattern)
    orderNum := orderRegex.FindString(text)
    fmt.Println("提取的订单号:", orderNum)
    
    // 提取价格数字
    pricePattern := `￥(\d+\.\d+)`
    priceRegex := regexp.MustCompile(pricePattern)
    priceMatches := priceRegex.FindAllStringSubmatch(text, -1)
    
    fmt.Println("提取的价格:")
    for _, match := range priceMatches {
        if len(match) > 1 {
            fmt.Println("  ", match[1])
        }
    }
    
    // 字符串构建器
    var builder strings.Builder
    builder.WriteString("产品清单:\n")
    products := []string{"笔记本电脑", "无线鼠标", "机械键盘", "显示器"}
    
    for i, product := range products {
        builder.WriteString(strconv.Itoa(i+1))
        builder.WriteString(". ")
        builder.WriteString(product)
        builder.WriteString("\n")
    }
    
    fmt.Println("\n" + builder.String())
    
    // 字符串替换和重复
    template := "重要通知: {message} | 重复显示: {repeat}"
    replaced := strings.Replace(template, "{message}", "系统维护通知", 1)
    repeated := strings.Repeat("注意!", 3)
    final := strings.Replace(replaced, "{repeat}", repeated, 1)
    fmt.Println(final)
    
    // 字符串比较和前缀后缀
    url1 := "https://example.com/api/v1/users"
    url2 := "https://example.com/api/v1/products"
    
    fmt.Printf("\nURL1 以 https 开头: %t\n", strings.HasPrefix(url1, "https"))
    fmt.Printf("URL2 以 users 结尾: %t\n", strings.HasSuffix(url2, "users"))
    fmt.Printf("URL1 和 URL2 包含相同API路径: %t\n", 
        strings.Contains(url1, "/api/v1/") && strings.Contains(url2, "/api/v1/"))
}

5. 课时总结