Question

How to reverse an integer number in Go

Answer 1

package main

import (
    "fmt"
)

func reverseNumber(n int) int {
    reverse := 0
    is_positive := 1

	if (n < 0) {
        is_positive = -1
        n = n * -1
    }

    for n > 0 {
        remainder := n % 10
        reverse *= 10
        reverse += remainder 
        n /= 10
    }
    
    if (is_positive == -1) {
        reverse = reverse * -1;
    }

    return reverse 
}

func main() {
    fmt.Println(reverseNumber(12345))
    fmt.Println(reverseNumber(130004))
    fmt.Println(reverseNumber(98000))
    fmt.Println(reverseNumber(-893))
}



/*
run:

54321
400031
89
-398

*/

 

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Answer 2

package main

import (
	"fmt"
	"strconv"
	"strings"
)

func reverseNumber(num float64) float64 {
	str := strconv.FormatFloat(num, 'f', -1, 64)

	arr := strings.Split(str, "")
	reverse(arr)
	str = strings.Join(arr, "")

	num, _ = strconv.ParseFloat(str, 64)

	return num
}

func reverse(s []string) {
	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
		s[i], s[j] = s[j], s[i]
	}
}

func main() {
    fmt.Println(reverseNumber(12345))
    fmt.Println(reverseNumber(130004))
    fmt.Println(reverseNumber(98000))
}



/*
run:

54321
400031
89

*/

 

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