Golang strings 包常用字串操作函數

目錄

1. func Contains

2. func HasPrefix

3. func HasSuffix

4. func Replace

5. func Split

6. func ToLower

7. func ToUpper

8. func Repeat

---

在編寫程式碼的時候最常用到的就是字串了，本篇文章將結合範例對常用的字串操作函數進行介紹。

1. func Contains

func Contains(s, substr string) bool

判斷 substr 是否是 s 的子串，例如：

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Contains("Linux", "in"))
	fmt.Println(strings.Contains("Linux", "Unix"))
	fmt.Println(strings.Contains("Linux", ""))
	fmt.Println(strings.Contains("", ""))
}

輸出：

true
false
true
true

2. func HasPrefix

func HasPrefix(s, prefix string) bool

字串 s 是否以 prefix 為開頭，例如：

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.HasPrefix("Linux", "Lin"))
	fmt.Println(strings.HasPrefix("Linux", "in"))
	fmt.Println(strings.HasPrefix("Linux", ""))
}

輸出：

true
false
true

3. func HasSuffix

func HasSuffix(s, suffix string) bool

判斷字串 s 是否以 suffix 結尾，例如：

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.HasSuffix("Linux", "nux"))
	fmt.Println(strings.HasSuffix("Linux", "ix"))
	fmt.Println(strings.HasSuffix("Linux", ""))
}

輸出為：

true
false
true

4. func Replace

func Replace(s, old, new string, n int) string

返回 s 中前 n 個不重複的 old 子串替換為 new 子串的新字串，如果 n < 0 ，則替換所有 old 子串，例如：

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Replace("Linux is very very very good!", "very", "much", 2))
	fmt.Println(strings.Replace("Linux is very very very good!", "very", "much", -1))
}

輸出為：

Linux is much much very good!
Linux is much much much good!

5. func Split

func Split(s, sep string) []string

返回將字串 s 按 sep子串分割的字串切片，sep 為空字串時，將 s 分割為每一個 unicode 碼值的字串切片。例如：

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Split("Linux, Unix, Windows, Android", ", "))
	fmt.Println(strings.Split(" Linux is very very very good! ", " "))
}

輸出為：返回的是字串陣列。

[Linux Unix Windows Android]
[ Linux is very very very good! ]

6. func ToLower

func ToLower(s string) string

返回字串 s 中字母轉小寫的拷貝，例如：

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.ToLower("Linux, Unix, Windows, Android"))
	fmt.Println(strings.ToLower(" Linux is very very very good! "))
}

輸出為：

linux, unix, windows, android
 linux is very very very good!

7. func ToUpper

func ToUpper(s string) string

返回字串 s 中字母轉大寫的拷貝，例如：

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.ToUpper("Linux, Unix, Windows, Android"))
	fmt.Println(strings.ToUpper(" Linux is very very very good! "))
}

輸出為：

LINUX, UNIX, WINDOWS, ANDROID
 LINUX IS VERY VERY VERY GOOD! 

8. func Repeat

func Repeat(s string, count int) string

返回 count 個字串 s 相連線的字串，如果 count 為負數 或（len * s * count）的結果溢位，則報 panic 異常。例如：

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Repeat("Linux", 6))
	fmt.Println(strings.Repeat("Linux", 0))
	fmt.Println(strings.Repeat("Linux", -1))
}

輸出為：

LinuxLinuxLinuxLinuxLinuxLinux

panic: strings: negative Repeat count

goroutine 1 [running]:
strings.Repeat(0x4bcf3d, 0x5, 0xffffffffffffffff, 0x1, 0x1)
        /usr/local/go/src/strings/strings.go:529 +0x5e5
main.main()
        /root/goProject/src/test/main.go:11 +0x167

參考連結：

https://golang.org/pkg/strings/