[golang] 字串操作的常見應用範例

 1. 字串連接

package main

import (
	"fmt"
	"strings"
)

func main() {
	// 使用 "+" 連接
	str1 := "Hello"
	str2 := "World"
	combined := str1 + " " + str2
	fmt.Println(combined) // Output: Hello World

	// 使用 strings.Join
	words := []string{"Go", "is", "awesome"}
	result := strings.Join(words, " ")
	fmt.Println(result) // Output: Go is awesome
}

---

2. 字串分割

package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "apple,banana,cherry"
	split := strings.Split(str, ",")
	fmt.Println(split) // Output: [apple banana cherry]
}

---

3. 字串搜尋

package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "Golang is fun!"
	// 搜尋子字串是否存在
	fmt.Println(strings.Contains(str, "fun")) // Output: true

	// 搜尋子字串的索引
	fmt.Println(strings.Index(str, "is")) // Output: 7
}

---

4. 字串取代

package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "I love cats, cats are cute."
	replaced := strings.ReplaceAll(str, "cats", "dogs")
	fmt.Println(replaced) // Output: I love dogs, dogs are cute.
}

---

5. 字串大小寫轉換

package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "Hello, Golang!"
	fmt.Println(strings.ToUpper(str)) // Output: HELLO, GOLANG!
	fmt.Println(strings.ToLower(str)) // Output: hello, golang!
}

---

6. 去除空白字元

package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "   Hello, Golang!   "
	trimmed := strings.TrimSpace(str)
	fmt.Println(trimmed) // Output: Hello, Golang!
}

---

7. 字串重複

package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "Go "
	repeated := strings.Repeat(str, 3)
	fmt.Println(repeated) // Output: Go Go Go 
}

---

8. 字串格式化

package main

import "fmt"

func main() {
	name := "Alice"
	age := 25
	formatted := fmt.Sprintf("My name is %s and I am %d years old.", name, age)
	fmt.Println(formatted) // Output: My name is Alice and I am 25 years old.
}

---

9. 字串反轉

package main

import "fmt"

func reverseString(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}
	return string(runes)
}

func main() {
	str := "Golang"
	reversed := reverseString(str)
	fmt.Println(reversed) // Output: gnalog
}

---

10. 檢查字串是否以某前綴或後綴開始/結束

package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "hello_world.go"

	// 是否以某前綴開始
	fmt.Println(strings.HasPrefix(str, "hello")) // Output: true

	// 是否以某後綴結束
	fmt.Println(strings.HasSuffix(str, ".go")) // Output: true
}