Merging other languages
This commit is contained in:
James Miranda
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en/07.6.md
314
en/07.6.md
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# 7.6 字符串处理
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字符串在我们平常的Web开发中经常用到，包括用户的输入，数据库读取的数据等，我们经常需要对字符串进行分割、连接、转换等操作，本小节将通过Go标准库中的strings和strconv两个包中的函数来讲解如何进行有效快速的操作。
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## 字符串操作
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下面这些函数来自于strings包，这里介绍一些我平常经常用到的函数，更详细的请参考官方的文档。
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- func Contains(s, substr string) bool
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字符串s中是否包含substr，返回bool值
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fmt.Println(strings.Contains("seafood", "foo"))
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fmt.Println(strings.Contains("seafood", "bar"))
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fmt.Println(strings.Contains("seafood", ""))
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fmt.Println(strings.Contains("", ""))
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//Output:
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//true
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//false
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//true
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//true
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- func Join(a []string, sep string) string
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字符串链接，把slice a通过sep链接起来
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s := []string{"foo", "bar", "baz"}
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fmt.Println(strings.Join(s, ", "))
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//Output:foo, bar, baz
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- func Index(s, sep string) int
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在字符串s中查找sep所在的位置，返回位置值，找不到返回-1
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fmt.Println(strings.Index("chicken", "ken"))
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fmt.Println(strings.Index("chicken", "dmr"))
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//Output:4
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//-1
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- func Repeat(s string, count int) string
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重复s字符串count次，最后返回重复的字符串
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fmt.Println("ba" + strings.Repeat("na", 2))
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//Output:banana
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- func Replace(s, old, new string, n int) string
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在s字符串中，把old字符串替换为new字符串，n表示替换的次数，小于0表示全部替换
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fmt.Println(strings.Replace("oink oink oink", "k", "ky", 2))
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fmt.Println(strings.Replace("oink oink oink", "oink", "moo", -1))
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//Output:oinky oinky oink
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//moo moo moo
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- func Split(s, sep string) []string
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把s字符串按照sep分割，返回slice
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fmt.Printf("%q\n", strings.Split("a,b,c", ","))
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fmt.Printf("%q\n", strings.Split("a man a plan a canal panama", "a "))
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fmt.Printf("%q\n", strings.Split(" xyz ", ""))
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fmt.Printf("%q\n", strings.Split("", "Bernardo O'Higgins"))
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//Output:["a" "b" "c"]
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//["" "man " "plan " "canal panama"]
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//[" " "x" "y" "z" " "]
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//[""]
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- func Trim(s string, cutset string) string
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在s字符串的头部和尾部去除cutset指定的字符串
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fmt.Printf("[%q]", strings.Trim(" !!! Achtung !!! ", "! "))
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//Output:["Achtung"]
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- func Fields(s string) []string
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去除s字符串的空格符，并且按照空格分割返回slice
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fmt.Printf("Fields are: %q", strings.Fields(" foo bar baz "))
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//Output:Fields are: ["foo" "bar" "baz"]
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## 字符串转换
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字符串转化的函数在strconv中，如下也只是列出一些常用的：
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- Append 系列函数将整数等转换为字符串后，添加到现有的字节数组中。
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package main
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import (
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"fmt"
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"strconv"
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)
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func main() {
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str := make([]byte, 0, 100)
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str = strconv.AppendInt(str, 4567, 10)
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str = strconv.AppendBool(str, false)
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str = strconv.AppendQuote(str, "abcdefg")
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str = strconv.AppendQuoteRune(str, '单')
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fmt.Println(string(str))
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}
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- Format 系列函数把其他类型的转换为字符串
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package main
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import (
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"fmt"
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"strconv"
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)
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func main() {
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a := strconv.FormatBool(false)
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b := strconv.FormatFloat(123.23, 'g', 12, 64)
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c := strconv.FormatInt(1234, 10)
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d := strconv.FormatUint(12345, 10)
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e := strconv.Itoa(1023)
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fmt.Println(a, b, c, d, e)
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}
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- Parse 系列函数把字符串转换为其他类型
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package main
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import (
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"fmt"
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"strconv"
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)
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func checkError(e error){
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if e != nil{
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fmt.Println(e)
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}
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}
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func main() {
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a, err := strconv.ParseBool("false")
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checkError(err)
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b, err := strconv.ParseFloat("123.23", 64)
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checkError(err)
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c, err := strconv.ParseInt("1234", 10, 64)
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checkError(err)
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d, err := strconv.ParseUint("12345", 10, 64)
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checkError(err)
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e, err := strconv.Atoi("1023")
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checkError(err)
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fmt.Println(a, b, c, d, e)
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}
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## links
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* [目录](<preface.md>)
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* 上一节: [文件操作](<07.5.md>)
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* 下一节: [小结](<07.7.md>)
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# 7.6 Strings
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On the web, almost everything we see (including user inputs, database access, etc.), is represented by strings. They are a very important part of web development. In many cases, we also need to split, join, convert and otherwise manipulate strings. In this section, we are going to introduce the `strings` and `strconv` packages from the Go standard library.
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## strings
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The following functions are from the `strings` package. See the official documentation for more details:
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- func Contains(s, substr string) bool
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Check if string `s` contains string `substr`, returns a boolean value.
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fmt.Println(strings.Contains("seafood", "foo"))
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fmt.Println(strings.Contains("seafood", "bar"))
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fmt.Println(strings.Contains("seafood", ""))
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fmt.Println(strings.Contains("", ""))
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//Output:
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//true
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//false
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//true
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//true
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- func Join(a []string, sep string) string
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Combine strings from slice with separator `sep`.
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s := []string{"foo", "bar", "baz"}
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fmt.Println(strings.Join(s, ", "))
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//Output:foo, bar, baz
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- func Index(s, sep string) int
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Find index of `sep` in string `s`, returns -1 if it's not found.
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fmt.Println(strings.Index("chicken", "ken"))
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fmt.Println(strings.Index("chicken", "dmr"))
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//Output:4
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//-1
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- func Repeat(s string, count int) string
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Repeat string `s` `count` times.
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fmt.Println("ba" + strings.Repeat("na", 2))
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//Output:banana
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- func Replace(s, old, new string, n int) string
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Replace string `old` with string `new` in string `s`. `n` is the number of replacements. If n is less than 0, replace all instances.
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fmt.Println(strings.Replace("oink oink oink", "k", "ky", 2))
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fmt.Println(strings.Replace("oink oink oink", "oink", "moo", -1))
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//Output:oinky oinky oink
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//moo moo moo
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- func Split(s, sep string) []string
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Split string `s` with separator `sep` into a slice.
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fmt.Printf("%q\n", strings.Split("a,b,c", ","))
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fmt.Printf("%q\n", strings.Split("a man a plan a canal panama", "a "))
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fmt.Printf("%q\n", strings.Split(" xyz ", ""))
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fmt.Printf("%q\n", strings.Split("", "Bernardo O'Higgins"))
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//Output:["a" "b" "c"]
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//["" "man " "plan " "canal panama"]
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//[" " "x" "y" "z" " "]
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//[""]
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- func Trim(s string, cutset string) string
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Remove `cutset` of string `s` if it's leftmost or rightmost.
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fmt.Printf("[%q]", strings.Trim(" !!! Achtung !!! ", "! "))
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Output:["Achtung"]
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- func Fields(s string) []string
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Remove space items and split string with space into a slice.
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fmt.Printf("Fields are: %q", strings.Fields(" foo bar baz "))
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//Output:Fields are: ["foo" "bar" "baz"]
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## strconv
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The following functions are from the `strconv` package. As usual, please see official documentation for more details:
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- Append series, convert data to string, and append to current byte slice.
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package main
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import (
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"fmt"
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"strconv"
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)
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func main() {
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str := make([]byte, 0, 100)
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str = strconv.AppendInt(str, 4567, 10)
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str = strconv.AppendBool(str, false)
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str = strconv.AppendQuote(str, "abcdefg")
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str = strconv.AppendQuoteRune(str, '单')
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fmt.Println(string(str))
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}
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- Format series, convert other data types into string.
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package main
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import (
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"fmt"
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"strconv"
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)
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func main() {
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a := strconv.FormatBool(false)
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b := strconv.FormatFloat(123.23, 'g', 12, 64)
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c := strconv.FormatInt(1234, 10)
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d := strconv.FormatUint(12345, 10)
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e := strconv.Itoa(1023)
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fmt.Println(a, b, c, d, e)
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}
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- Parse series, convert strings to other types.
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package main
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import (
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"fmt"
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"strconv"
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)
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func main() {
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a, err := strconv.ParseBool("false")
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if err != nil {
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fmt.Println(err)
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}
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b, err := strconv.ParseFloat("123.23", 64)
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if err != nil {
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fmt.Println(err)
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}
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c, err := strconv.ParseInt("1234", 10, 64)
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if err != nil {
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fmt.Println(err)
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}
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d, err := strconv.ParseUint("12345", 10, 64)
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if err != nil {
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fmt.Println(err)
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}
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e, err := strconv.Itoa("1023")
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if err != nil {
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fmt.Println(err)
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}
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fmt.Println(a, b, c, d, e)
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}
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## Links
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- [Directory](preface.md)
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- Previous section: [Files](07.5.md)
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- Next section: [Summary](07.7.md)
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