Golang 获取字符串中，相同字符出现的次数

方法一：先统计，然后根据key进行排序输出

str := "ERWQREEIUWQJNCDSCMKLSADASDPSADOPISAPD"
    map1 := make(map[int]int)
    for i := 0; i < len(str); i++ {
        if map1[int(str[i])] == 0 {
            map1[int(str[i])] = 1
        } else if map1[int(str[i])] > 0 {
            num := map1[int(str[i])]
            map1[int(str[i])] = num + 1
        }
    }
    for key,count:= range map1 {
        fmt.Printf("%c : %d   \n",key,count)
    }

    keys := make([]int, 0, len(map1))
    for key := range map1 {
        keys = append(keys, int(key))
    }
    sort.Ints(keys)
    for _ ,key := range keys {
        fmt.Printf("%c : %d \n",key,map1[key])
    }

方法二：限制了必须是纯字母的字符串

    for i := 'A'; i <= 'Z'; i++ {
        count := 0
        for j := 0; j < len(str); j++ {
            if i == int32(str[j]) {
                count++
            }
        }
        if count > 0 {
            fmt.Printf("%c : %d \n", i, count)
        }
    }

方法三：也是限制了必须是纯字母的字符串,i是rune类型 需要转换成string

    for i:='A';i<='Z'; i++ {
        
        fmt.Printf("%s : %d \n",string(i),strings.Count(str,string(i)))

    }