从字符串中删除空字符

Question

我想检查字符串是否为空并及时解析字符串。

请找到下面的代码

valueStr = strings.Replace(string(valueStr), " ", "", -1)

valueStr = strings.Replace(string(valueStr), "\t", "", -1)

valueStr = strings.Replace(string(valueStr), "\n", "", -1)

valueStr = strings.Replace(string(valueStr), "\r", "", -1)

var re = regexp.MustCompile(`\s`)

valueStr = re.ReplaceAllString(valueStr, "")

if valueStr != "" {

    fmt.Printf("-------- valueStr %c: \n", valueStr)         // o/p =>  -------- valueStr %!c(string= ):

    fmt.Printf("-------- valueStr %#v: \n", valueStr)        // o/p => -------- valueStr "\x00":

    fmt.Printf("-------- valueStr %x: \n", valueStr)         // o/p =>  -------- valueStr 00:

    fmt.Println("-------- valueStr length: ", len(valueStr)) // o/p => -------- valueStr length:  1

    // considering valueStr is not empty, parse string to time

    time, err := time.Parse(TIME_FORMAT, strings.TrimSpace(valueStr))

    if err != nil {

        fmt.Println("-------- Error converting time: ", err) // o/p => -------- Error converting time:  parsing time " " as "15:04:05": cannot parse " " as "15"

        return

    }

} else {

    // another code

}

如何从字符串中删除这个空字符？或者检查字符串是否包含这个空字符？

Answer 1

您可以\x00像删除任何其他符文一样从字符串中删除符文：valueStr = strings.Replace(valueStr, "\x00", "", -1)例子：s := "a\x00b"fmt.Printf("%q\n", s)s = strings.Replace(s, "\x00", "", -1)fmt.Printf("%q\n", s)输出（在Go Playground上尝试）："a\x00b""ab"使用strings.Replacer另请注意，您可以使用 将多个替换替换为单个操作 strings.Replacer，并且它也会更有效，因为它只对输入进行一次迭代（并且只会string为结果分配一个，无论您想要多少个子字符串取代）。例如：s := " \t\n\rabc\x00"fmt.Printf("%q\n", s)r := strings.NewReplacer(" ", "", "\t", "", "\n", "", "\r", "", "\x00", "")s = r.Replace(s)fmt.Printf("%q\n", s)输出（在Go Playground上尝试）：" \t\n\rabc\x00""abc"另请注意，创建string.Replacer一次就足够了，您可以将它存储在一个（全局）变量中并重用它，从多个 goroutines 同时使用它甚至是安全的。使用strings.Map()另请注意，如果您只想替换（删除）单个runes 而不是多符文（或多字节）子字符串，您还可以使用strings.Map()which 可能比strings.Replacer.首先定义一个函数，告诉rune要替换哪些 s（如果返回负值则删除）：func remove(r rune) rune {&nbsp; &nbsp; switch r {&nbsp; &nbsp; case ' ', '\t', '\n', '\r', 0:&nbsp; &nbsp; &nbsp; &nbsp; return -1&nbsp; &nbsp; }&nbsp; &nbsp; return r}然后使用它：s := " \t\n\rabc\x00"fmt.Printf("%q\n", s)s = strings.Map(remove, s)fmt.Printf("%q\n", s)输出（在Go Playground上尝试）：" \t\n\rabc\x00""abc"基准我们可能会认为strings.Map()它会更好，因为它只需要处理rune只是数字的 s int32，而strings.Replacer必须处理string标头（长度+数据指针）加上一系列字节的值。但是我们应该知道，string值在内存中存储为 UTF-8 字节序列，这意味着strings.Map()必须rune从 UTF-8 字节序列中解码 s（并最终将符文编码回 UTF-8），而不会strings.Replacer：它可能只是寻找字节序列匹配而不对runes 进行解码。并且strings.Replacer经过高度优化以利用此类“技巧”。因此，让我们创建一个基准来比较它们：我们将使用这些作为基准：var r = strings.NewReplacer(" ", "", "\t", "", "\n", "", "\r", "", "\x00", "")func remove(r rune) rune {&nbsp; &nbsp; switch r {&nbsp; &nbsp; case ' ', '\t', '\n', '\r', 0:&nbsp; &nbsp; &nbsp; &nbsp; return -1&nbsp; &nbsp; }&nbsp; &nbsp; return r}我们在不同的输入字符串上运行基准测试：func BenchmarkReplaces(b *testing.B) {&nbsp; &nbsp; cases := []struct {&nbsp; &nbsp; &nbsp; &nbsp; title string&nbsp; &nbsp; &nbsp; &nbsp; input string&nbsp; &nbsp; }{&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; title: "None",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; input: "abc",&nbsp; &nbsp; &nbsp; &nbsp; },&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; title: "Normal",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; input: " \t\n\rabc\x00",&nbsp; &nbsp; &nbsp; &nbsp; },&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; title: "Long",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; input: "adsfWR \t\rab\nc\x00 \t\n\rabc\x00asdfWER\n\r",&nbsp; &nbsp; &nbsp; &nbsp; },&nbsp; &nbsp; }&nbsp; &nbsp; for _, c := range cases {&nbsp; &nbsp; &nbsp; &nbsp; b.Run("Replacer-"+c.title, func(b *testing.B) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for i := 0; i < b.N; i++ {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; r.Replace(c.input)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; })&nbsp; &nbsp; &nbsp; &nbsp; b.Run("Map-"+c.title, func(b *testing.B) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for i := 0; i < b.N; i++ {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; strings.Map(remove, c.input)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; })&nbsp; &nbsp; }}现在让我们看看基准测试结果：BenchmarkReplaces/Replacer-None-4&nbsp; &nbsp; 100000000&nbsp; &nbsp;12.3 ns/op&nbsp; &nbsp; 0 B/op&nbsp; 0 allocs/opBenchmarkReplaces/Map-None-4&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;100000000&nbsp; &nbsp;16.1 ns/op&nbsp; &nbsp; 0 B/op&nbsp; 0 allocs/opBenchmarkReplaces/Replacer-Normal-4&nbsp; 20000000&nbsp; &nbsp; 92.7 ns/op&nbsp; &nbsp; 6 B/op&nbsp; 2 allocs/opBenchmarkReplaces/Map-Normal-4&nbsp; &nbsp; &nbsp; &nbsp;20000000&nbsp; &nbsp; 92.4 ns/op&nbsp; &nbsp;16 B/op&nbsp; 2 allocs/opBenchmarkReplaces/Replacer-Long-4&nbsp; &nbsp; &nbsp;5000000&nbsp; &nbsp;234 ns/op&nbsp; &nbsp; &nbsp;64 B/op&nbsp; 2 allocs/opBenchmarkReplaces/Map-Long-4&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 5000000&nbsp; &nbsp;235 ns/op&nbsp; &nbsp; &nbsp;80 B/op&nbsp; 2 allocs/op尽管有预期，但string.Replacer表现相当不错，strings.Map()因为它不需要解码和编码符文。

Answer 2

在当前的 Python（截至 2021 年 11 月）和 Windows 10 下，这段代码对我有用：s&nbsp;=&nbsp;str.replace(s,&nbsp;"\x00",&nbsp;"",&nbsp;-1)

Answer 3

我不知道这是否是您的情况，但就我而言，我收到了uint16来自 Windows Syscalls 的切片。在这种情况下，数据也由 null 元素终止。为了解决这个问题，你可以使用这个windows包：package mainimport (   "fmt"   "golang.org/x/sys/windows")func main() {   a := []uint16{77, 97, 114, 99, 104, 0}   s := windows.UTF16ToString(a)   fmt.Printf("%q\n", s) // "March"}