string_reverse.go

package main

import "fmt"

func reverse(s string) string {
	runes := []rune(s)
	n, h := len(runes), len(runes)/2
	for i := 0; i < h; i++ {
		runes[i], runes[n-1-i] = runes[n-1-i], runes[i]
	}
	return string(runes)
}

func main() {
	// reverse a string:
	str := "Google"
	sl := []byte(str)
	var rev [100]byte
	j := 0
	for i := len(sl) - 1; i >= 0; i-- {
		rev[j] = sl[i]
		j++
	}
	str_rev := string(rev[:])
	fmt.Printf("The reversed string is -%s-\n", str_rev)
	// variant: "in place" using swapping
	str2 := "Google"
	sl2 := []byte(str2)
	for i, j := 0, len(sl2)-1; i < j; i, j = i+1, j-1 {
		sl2[i], sl2[j] = sl2[j], sl2[i]
	}
	fmt.Printf("The reversed string is -%s-\n", string(sl2))
	// variant: using [] int for runes (necessary for Unicode-strings!):
	s := "My Test String!"
	fmt.Println(s, " --> ", reverse(s))
}

/* Output:
The reversed string is -elgooG-
The reversed string is -elgooG-
My Test String!  -->  !gnirtS tseT yM
*/