s := "Hello王"
sHello := "Hello"
sWang := "王"
//len()獲得的是 byte 字節(jié)的數(shù)量
fmt.Println(len(s))
fmt.Println(len(sHello))
fmt.Println(len(sWang))

s := "Hello王"
for i := 0; i < len(s); i++ {
   fmt.Printf("%c\n", s[i])
}

s := "Hello王"
for _, c := range s {
   fmt.Printf("%c\n", c) //%c 字符
}

s2 := "小白兔"
s3 := []rune(s2)        //把字符串強制轉(zhuǎn)成rune切片
s3[0] = '大'             //注意 這里需要使用單引號的字符，而不是雙引號的字符串
fmt.Println(string(s3)) //把rune類型的s3強轉(zhuǎn)成字符串

c1 := "紅"
c2 := '紅'                            
fmt.Printf("c1的類型:%T c2的類型:%T \n", c1, c2) 
c3 := "H"                            
c4 := 'H'                            
fmt.Printf("c3的類型:%T c4的類型:%T \n", c3, c4)

c1的類型:string c2的類型:int32 
c3的類型:string c4的類型:int32

n1 := 10
var f float64
f = float64(n1)
fmt.Printf("f的類型是：%T f的值是：%v\n", f,f)

f的類型是：float64 f的值是：10