182 lines
4.1 KiB
Markdown
182 lines
4.1 KiB
Markdown
# 7.6 字串處理
|
||
字串在我們平常的Web開發中經常用到，包括使用者的輸入，資料庫讀取的資料等，我們經常需要對字串進行分割、連線、轉換等操作，本小節將透過Go標準函式庫中的strings和strconv兩個套件中的函式來講解如何進行有效快速的操作。
|
||
## 字串操作
|
||
下面這些函式來自於strings套件，這裡介紹一些我平常經常用到的函式，更詳細的請參考官方的文件。
|
||
|
||
- func Contains(s, substr string) bool
|
||
|
||
字串s中是否包含substr，返回bool值
|
||
|
||
```Go
|
||
|
||
fmt.Println(strings.Contains("seafood", "foo"))
|
||
fmt.Println(strings.Contains("seafood", "bar"))
|
||
fmt.Println(strings.Contains("seafood", ""))
|
||
fmt.Println(strings.Contains("", ""))
|
||
//Output:
|
||
//true
|
||
//false
|
||
//true
|
||
//true
|
||
|
||
```
|
||
|
||
- func Join(a []string, sep string) string
|
||
|
||
字串連結，把slice a透過sep連結起來
|
||
|
||
```Go
|
||
|
||
s := []string{"foo", "bar", "baz"}
|
||
fmt.Println(strings.Join(s, ", "))
|
||
//Output:foo, bar, baz
|
||
```
|
||
|
||
- func Index(s, sep string) int
|
||
|
||
在字串s中查詢sep所在的位置，返回位置值，找不到返回-1
|
||
|
||
```Go
|
||
|
||
fmt.Println(strings.Index("chicken", "ken"))
|
||
fmt.Println(strings.Index("chicken", "dmr"))
|
||
//Output:4
|
||
//-1
|
||
```
|
||
- func Repeat(s string, count int) string
|
||
|
||
重複s字串count次，最後返回重複的字串
|
||
|
||
```Go
|
||
|
||
fmt.Println("ba" + strings.Repeat("na", 2))
|
||
//Output:banana
|
||
```
|
||
- func Replace(s, old, new string, n int) string
|
||
|
||
在s字串中，把old字串替換為new字串，n表示替換的次數，小於0表示全部替換
|
||
|
||
```Go
|
||
|
||
fmt.Println(strings.Replace("oink oink oink", "k", "ky", 2))
|
||
fmt.Println(strings.Replace("oink oink oink", "oink", "moo", -1))
|
||
//Output:oinky oinky oink
|
||
//moo moo moo
|
||
```
|
||
- func Split(s, sep string) []string
|
||
|
||
把s字串按照sep分割，返回slice
|
||
|
||
```Go
|
||
|
||
fmt.Printf("%q\n", strings.Split("a,b,c", ","))
|
||
fmt.Printf("%q\n", strings.Split("a man a plan a canal panama", "a "))
|
||
fmt.Printf("%q\n", strings.Split(" xyz ", ""))
|
||
fmt.Printf("%q\n", strings.Split("", "Bernardo O'Higgins"))
|
||
//Output:["a" "b" "c"]
|
||
//["" "man " "plan " "canal panama"]
|
||
//[" " "x" "y" "z" " "]
|
||
//[""]
|
||
```
|
||
|
||
- func Trim(s string, cutset string) string
|
||
|
||
在s字串的頭部和尾部去除cutset指定的字串
|
||
|
||
```Go
|
||
|
||
fmt.Printf("[%q]", strings.Trim(" !!! Achtung !!! ", "! "))
|
||
//Output:["Achtung"]
|
||
```
|
||
|
||
- func Fields(s string) []string
|
||
|
||
去除s字串的空格符，並且按照空格分割返回slice
|
||
|
||
```Go
|
||
|
||
fmt.Printf("Fields are: %q", strings.Fields(" foo bar baz "))
|
||
//Output:Fields are: ["foo" "bar" "baz"]
|
||
```
|
||
|
||
## 字串轉換
|
||
字串轉化的函式在strconv中，如下也只是列出一些常用的：
|
||
|
||
- Append 系列函式將整數等轉換為字串後，新增到現有的位元組陣列中。
|
||
|
||
```Go
|
||
|
||
package main
|
||
|
||
import (
|
||
"fmt"
|
||
"strconv"
|
||
)
|
||
|
||
func main() {
|
||
str := make([]byte, 0, 100)
|
||
str = strconv.AppendInt(str, 4567, 10)
|
||
str = strconv.AppendBool(str, false)
|
||
str = strconv.AppendQuote(str, "abcdefg")
|
||
str = strconv.AppendQuoteRune(str, '單')
|
||
fmt.Println(string(str))
|
||
}
|
||
```
|
||
|
||
- Format 系列函式把其他型別的轉換為字串
|
||
```Go
|
||
|
||
package main
|
||
|
||
import (
|
||
"fmt"
|
||
"strconv"
|
||
)
|
||
|
||
func main() {
|
||
a := strconv.FormatBool(false)
|
||
b := strconv.FormatFloat(123.23, 'g', 12, 64)
|
||
c := strconv.FormatInt(1234, 10)
|
||
d := strconv.FormatUint(12345, 10)
|
||
e := strconv.Itoa(1023)
|
||
fmt.Println(a, b, c, d, e)
|
||
}
|
||
|
||
```
|
||
|
||
- Parse 系列函式把字串轉換為其他型別
|
||
|
||
```Go
|
||
|
||
package main
|
||
|
||
import (
|
||
"fmt"
|
||
"strconv"
|
||
)
|
||
func checkError(e error){
|
||
if e != nil{
|
||
fmt.Println(e)
|
||
}
|
||
}
|
||
func main() {
|
||
a, err := strconv.ParseBool("false")
|
||
checkError(err)
|
||
b, err := strconv.ParseFloat("123.23", 64)
|
||
checkError(err)
|
||
c, err := strconv.ParseInt("1234", 10, 64)
|
||
checkError(err)
|
||
d, err := strconv.ParseUint("12345", 10, 64)
|
||
checkError(err)
|
||
e, err := strconv.Atoi("1023")
|
||
checkError(err)
|
||
fmt.Println(a, b, c, d, e)
|
||
}
|
||
|
||
```
|
||
|
||
## links
|
||
* [目錄](<preface.md>)
|
||
* 上一節: [檔案操作](<07.5.md>)
|
||
* 下一節: [小結](<07.7.md>)
|