Golang special user defined data types with additional behavior

special.go

package special

import (
	"fmt"
	"strconv"
)

// Special Type: int as Integer
type Integer int

// Format an Integer data to string
func (x Integer) ToString() string {
	return strconv.Itoa(int(x))
}

// Special Type: float64 as Float
type Float float64

// Format a Float data to string with 6 digit precision
func (x Float) ToString() string {
	return fmt.Sprintf("%f", x)
}

// Special Type: string as String
type String string

// Format a String data into lowercase letter
func (str String) ToLowercase() string {
	strByte := []byte{}
	for i := 0; i < len(str); i++ {
		if str[i] >= 65 && str[i] <= 90 {
			strByte = append(strByte, str[i]+32)
		} else {
			strByte = append(strByte, str[i])
		}
	}

	return string(strByte)
}

// Format a String data into uppercase letter
func (str String) ToUppercase() string {
	strByte := []byte{}
	for i := 0; i < len(str); i++ {
		if str[i] >= 97 && str[i] <= 122 {
			strByte = append(strByte, str[i]-32)
		} else {
			strByte = append(strByte, str[i])
		}
	}

	return string(strByte)
}

// Reverse String data's character set
func (str String) Reverse() string {
	strByte := []byte{}
	for i := len(str) - 1; i >= 0; i-- {
		strByte = append(strByte, str[i])
	}

	return string(strByte)
}