将unicode字符存储在golang中

Question

I'm creating a data structure for storing single unicode characters which I can then compare.

Two Questions:

1. What data types do I use?

   type ds struct { char Char // What should Char be so that I can safely compare two ds? }

2. I need a way to compare the first character of any two unicode strings. Is there a simple way to do that? Basically, how do I retrieve the first unicode character of a string?

Answer 1

Like this: type Char rune .

Pay attention to "compare", that is a complicated thing with Unicode. While code points ( rune s) are easy to compare numerically (U+0020 == U+0020; U+1234 < U+2345) this might or might not be what you want given case, combining characters and what else Unicode offers.

Answer 2

2. To compare utf8 strings, you need to check their runevalue. Runevalue is int32 value of utf8 character. Use standard package "unicode/utf8". Pass "string[0:]" to get the first character

     test := "春节" runeValue, width := utf8.DecodeRuneInString(test[0:]) fmt.Println(runeValue,width) fmt.Printf("%#U %d", runeValue, runeValue) 

Now you can compare runeValue of two strings's first character using == operator

1. Also you need to store string in string if you want to store whole character.

    type ds struct { char string // What should Char be so that I can safely compare two ds? } 

Complete code demonstrating this:

package main

import (
    "fmt"
    "unicode/utf8"
)

type ds struct {
    char string // What should Char be so that I can safely compare two ds?
}

func main() {
    fmt.Println("Hello, playground")

    ds1 := ds{"春节"}
    ds2 := ds{"春节"}

    runeValue1, _ := utf8.DecodeRuneInString(ds1.char[0:])
    runeValue2, _ := utf8.DecodeRuneInString(ds2.char[0:])

    fmt.Printf("%#U %#U", runeValue1, runeValue2)

    if runeValue1 == runeValue2 {
        fmt.Println("\nFirst Char Same")
    } else {
        fmt.Println("\nDifferent")
    }
}

Golang Playground

Answer 3

From Volkers, answer, we can just use rune to compare.

1. type Char rune
2. to get the first unicode character we can simply do []rune(str)[0]