查找、決議和驗證電子郵件地址

 import "fmt"

func main() {
    email := "[email protected]"
    atTrue := false
    s := ""
    for i := 0; i < len(email); i   {
        if atTrue {
            s  = string(email[i])
        }
        if string(email[i]) == "@" {
            atTrue = true
        }
    }
    fmt.Println(s)
}

電流輸出：gmail.com

期望輸出：域：gmail和 TLD：com

如何指示從某個字串到某個字串的回圈？

uj5u.com熱心網友回復：

使用strings.Split函式

    email := "[email protected]"
    split := strings.Split(email, "@")
    split = strings.Split(split[1], ".")
    fmt.Println("Domain:", split[0])
    fmt.Println("TLD:", split[1])

可選地，您可以使用mail.ParseAddress函式驗證電子郵件字串

    email := "[email protected]"
    addr, err := mail.ParseAddress(email)
    if err != nil {
        log.Fatal(err)
    }

如果 TLD 像這個 co.id 一樣，輸出仍然是 co.id 怎么辦？– @zacharyy

只需嘗試找到第一個index（.strings.Index ）并使用一個來分隔字串

    email := "[email protected]"
    split := strings.Split(email, "@")
    index := strings.Index(split[1], ".")
    fmt.Println("Domain:", split[1][:index])
    fmt.Println("TLD:", split[1][index 1:])

或使用regexp.Split函式

    email := "[email protected]"
    split := strings.Split(email, "@")
    split = regexp.MustCompile("[.]").
        Split(split[1], 2)
    fmt.Println("Domain:", split[0])
    fmt.Println("TLD:", split[1])

或strings.SplitN

    email := "[email protected]"
    split := strings.Split(email, "@")
    split = strings.SplitN(split[1], ".", 2)
    fmt.Println("Domain:", split[0])
    fmt.Println("TLD:", split[1])

或strings.Cut

    _, host, found := strings.Cut(email, "@")
    if !found {
        t.Fatal("fail cut to host (Domain   TLD)")
    }
    domain, tld, found := strings.Cut(host, ".")
    if !found {
        t.Fatal("fail cut to Domain and TLD")
    }
    fmt.Println("Domain:", domain)
    fmt.Println("TLD:", tld)

???????? PLAYGROUND_

基準

    const (
        quantity   = 10000
        userLength = 10
        domain     = "gmail.com"
    )
    var (
        letterRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
        emails      = make([]string, 0, quantity)
        seeded      = rand.New(rand.NewSource(time.Now().UnixMilli()))
    )

    for i := 0; i < quantity; i   {
        user := make([]rune, userLength)
        for i := range user {
            user[i] = letterRunes[seeded.Intn(len(letterRunes))]
        }
        emails = append(emails, fmt.Sprintf("%s@%s", string(user), domain))
    }

    b.Run("strings.Split", func(b *testing.B) {
        b.ReportAllocs()
        b.ResetTimer()
        var domain, tld string
        for i := 0; i < b.N; i   {
            for _, email := range emails {
                domain, tld = stringsSplit(email)
            }
        }
        _, _ = domain, tld
    })
    b.Run("strings.SplitN", func(b *testing.B) {
        b.ReportAllocs()
        b.ResetTimer()
        var domain, tld string
        for i := 0; i < b.N; i   {
            for _, email := range emails {
                domain, tld = stringsSplitN(email)
            }
        }
        _, _ = domain, tld
    })
    b.Run("strings.Index strings.Split", func(b *testing.B) {
        b.ReportAllocs()
        b.ResetTimer()
        var domain, tld string
        for i := 0; i < b.N; i   {
            for _, email := range emails {
                domain, tld = stringsIndexAndStringsSplit(email)
            }
        }
        _, _ = domain, tld
    })
    b.Run("regexp.Split", func(b *testing.B) {
        b.ReportAllocs()
        b.ResetTimer()
        var domain, tld string
        for i := 0; i < b.N; i   {
            for _, email := range emails {
                domain, tld = regexpSplit(email)
            }
        }
        _, _ = domain, tld
    })
    b.Run("strings.Cut", func(b *testing.B) {
        b.ReportAllocs()
        b.ResetTimer()
        var domain, tld string
        for i := 0; i < b.N; i   {
            for _, email := range emails {
                domain, tld = stringsCut(email)
            }
        }
        _, _ = domain, tld
    })

cpu: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
Benchmark
Benchmark/strings.Split
Benchmark/strings.Split-12                  752    1563851 ns/op      640002 B/op      20000 allocs/op
Benchmark/strings.SplitN
Benchmark/strings.SplitN-12                 805    1463329 ns/op      640003 B/op      20000 allocs/op
Benchmark/strings.Index strings.Split
Benchmark/strings.Index strings.Split-12   1416     858783 ns/op      320000 B/op      10000 allocs/op
Benchmark/regexp.Split
Benchmark/regexp.Split-12                    85   14605240 ns/op    11088513 B/op     160024 allocs/op
Benchmark/strings.Cut
Benchmark/strings.Cut-12                   6597     180579 ns/op           0 B/op          0 allocs/op
PASS

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