在 Go 中如何循环遍历一个字符串？

我想这样:

for i := 0; i < len(str); i++ {
dosomethingwithrune(str[i]) // takes a rune
}

但事实证明，str[i]的类型是 byte(uint8)而不是 rune。

如何通过符号而不是字节来迭代字符串？

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最佳答案

See this example from Effective Go :

for pos, char := range "日本語" {
fmt.Printf("character %c starts at byte position %d\n", char, pos)
}

This prints :

character 日 starts at byte position 0
character 本 starts at byte position 3
character 語 starts at byte position 6

For strings, the range does more work for you, breaking out individual Unicode code points by parsing the UTF-8.

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For example:

package main


import "fmt"


func main() {
for i, rune := range "Hello, 世界" {
fmt.Printf("%d: %c\n", i, rune)
}
}

Playground

Output:

0: H
1: e
2: l
3: l
4: o
5: ,
6:
7: 世
10: 界
小开

To mirror an example given at golang.org, Go allows you to easily convert a string to a slice of runes and then iterate over that, just like you wanted to originally:

runes := []rune("Hello, 世界")
for i := 0; i < len(runes) ; i++ {
fmt.Printf("Rune %v is '%c'\n", i, runes[i])
}

Of course, we could also use a range operator like in the other examples here, but this more closely follows your original syntax. In any case, this will output: 

Rune 0 is 'H'
Rune 1 is 'e'
Rune 2 is 'l'
Rune 3 is 'l'
Rune 4 is 'o'
Rune 5 is ','
Rune 6 is ' '
Rune 7 is '世'
Rune 8 is '界'

Note that since the rune type is an alias for int32, we must use %c instead of the usual %v in the Printf statement, or we will see the integer representation of the Unicode code point (see A Tour of Go).


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