Phrase reversals

Phrase reversals
You are encouraged to solve this task according to the task description, using any language you may know.

Given a string of space separated words containing the following phrase:

"rosetta code phrase reversal"

1. Reverse the string.
2. Reverse each individual word in the string, maintaining original string order.
3. Reverse the order of each word of the phrase, maintaining the order of characters in each word.

Show your output here.

See also

• Reverse a string
• Reverse words in a string

Ada

To split a string into words, the package "Simple_Parse" from another task [[1]] is used.

<lang Ada><with Ada.Text_IO, Simple_Parse;

procedure Phrase_Reversal is

  function Reverse_String (Item : String) return String is
     Result : String (Item'Range);
  begin
     for I in Item'range loop
        Result (Result'Last - I + Item'First) := Item (I);
     end loop;
     return Result;
  end Reverse_String;
  
  function Reverse_Words(S: String) return String is
     Cursor: Positive := S'First;
     Word: String := Simple_Parse.Next_Word(S, Cursor);
  begin
     if Cursor > S'Last then -- Word holds the last word 

return Reverse_String(Word);

     else

return Reverse_String(Word) & " " & Reverse_Words(S(Cursor .. S'Last));

     end if;
  end Reverse_Words;
  
  function Reverse_Order(S: String) return String is
     Cursor: Positive := S'First;
     Word: String := Simple_Parse.Next_Word(S, Cursor);
  begin
     if Cursor > S'Last then -- Word holds the last word 

return Word;

     else

return Reverse_Order(S(Cursor .. S'Last)) & " " & Word;

     end if;
  end Reverse_Order;
  
  Phrase: String := "rosetta code phrase reversal";
  use Ada.Text_IO;

begin

  Put_Line("0. The original phrase:       """ & Phrase & """");
  Put_Line("1. Reverse the entire phrase: """ & Reverse_String(Phrase) & """");
  Put_Line("2. Reverse words, same order: """ & Reverse_Words(Phrase) & """");
  Put_Line("2. Reverse order, same words: """ & Reverse_Order(Phrase) & """");

end Phrase_Reversal;</lang>

Output:

0. The original phrase:       "rosetta code phrase reversal"
1. Reverse the entire phrase: "lasrever esarhp edoc attesor"
2. Reverse words, same order: "attesor edoc esarhp lasrever"
2. Reverse order, same words: "reversal phrase code rosetta"

AWK

<lang awk># Usage: awk -f phrase_revers.awk function rev(s, del, n,i,a,r) {

  n = split(s, a, del)
  r = a[1]
  for(i=2; i <= n; i++) {r = a[i] del r }    
  return r

}

BEGIN {

 p0 = "Rosetta Code Phrase Reversal"

 fmt = "%-20s: %s\n"
 printf( fmt, "input",               p0 )
 printf( fmt, "string reversed",     rev(p0, "") )
 wr = rev(p0, " ")
 printf( fmt, "word-order reversed", wr )
 printf( fmt, "each word reversed",  rev(wr) )

}</lang>

Output:

input               : Rosetta Code Phrase Reversal
string reversed     : lasreveR esarhP edoC attesoR
word-order reversed : Reversal Phrase Code Rosetta
each word reversed  : attesoR edoC esarhP lasreveR

C

Working with C strings is often long-winded. <lang C>

1. include <stdio.h>
2. include <string.h>

/* The functions used are destructive, so after each call the string needs

* to be copied over again. One could easily allocate new strings as
* required, but this way allows the caller to manage memory themselves */

char* reverse_section(char *s, size_t length) {

   if (length == 0) return s;

   size_t i; char temp;
   for (i = 0; i < length / 2 + 1; ++i)
       temp = s[i], s[i] = s[length - i], s[length - i] = temp;
   return s;

}

char* reverse_words_in_order(char *s, char delim) {

   if (!strlen(s)) return s;

   size_t i, j;
   for (i = 0; i < strlen(s) - 1; ++i) {
       for (j = 0; s[i + j] != 0 && s[i + j] != delim; ++j)
           ;
       reverse_section(s + i, j - 1);
       s += j;
   }
   return s;

}

char* reverse_string(char *s) {

   return strlen(s) ? reverse_section(s, strlen(s) - 1) : s;

}

char* reverse_order_of_words(char *s, char delim) {

   reverse_string(s);
   reverse_words_in_order(s, delim);
   return s;

}

int main(void) {

   char str[]    = "rosetta code phrase reversal";
   size_t lenstr = sizeof(str) / sizeof(str[0]);
   char scopy[lenstr];
   char delim = ' ';

   /* Original String */
   printf("Original:       \"%s\"\n", str);

   /* Reversed string */
   strncpy(scopy, str, lenstr);
   reverse_string(scopy);
   printf("Reversed:       \"%s\"\n", scopy);

   /* Reversed words in string */
   strncpy(scopy, str, lenstr);
   reverse_words_in_order(scopy, delim);
   printf("Reversed words: \"%s\"\n", scopy);

   /* Reversed order of words in string */
   strncpy(scopy, str, lenstr);
   reverse_order_of_words(scopy, delim);
   printf("Reversed order: \"%s\"\n", scopy);

   return 0;

} </lang>

Output:

Original:       "rosetta code phrase reversal"
Reversed:       "lasrever esarhp edoc attesor"
Reversed words: "attesor edoc esarhp lasrever"
Reversed order: "reversal phrase code rosetta"

D

Partially lazy. <lang d>void main() {

   import std.stdio, std.range;

   immutable phrase = "rosetta code phrase reversal";
   phrase.retro.writeln;                          // Reversed string.
   phrase.splitter.map!retro.joiner(" ").writeln; // Words reversed.
   phrase.split.retro.joiner(" ").writeln;        // Word order reversed.

}</lang>

Output:

lasrever esarhp edoc attesor
attesor edoc esarhp lasrever
reversal phrase code rosetta

Go

Simple

<lang go>package main

import ( "fmt" "strings" )

const phrase = "rosetta code phrase reversal"

func revStr(s string) string { rs := make([]rune, len(s)) i := len(s) for _, r := range s { i-- rs[i] = r } return string(rs[i:]) }

func main() { fmt.Println("Reversed: ", revStr(phrase))

ws := strings.Fields(phrase) for i, w := range ws { ws[i] = revStr(w) } fmt.Println("Words reversed: ", strings.Join(ws, " "))

ws = strings.Fields(phrase) last := len(ws) - 1 for i, w := range ws[:len(ws)/2] { ws[i], ws[last-i] = ws[last-i], w } fmt.Println("Word order reversed:", strings.Join(ws, " ")) }</lang>

Output:

Reversed:            lasrever esarhp edoc attesor
Words reversed:      attesor edoc esarhp lasrever
Word order reversed: reversal phrase code rosetta

Alternative

<lang go>package main

import ( "fmt" "regexp" "sort" "strings" )

const phrase = "rosetta code phrase reversal"

type reversible interface { Len() int Swap(i, j int) }

func reverse(p reversible) { mid := p.Len() / 2 last := p.Len() - 1 for i := 0; i < mid; i++ { p.Swap(i, last-i) } }

type runeSlice []rune

func (p runeSlice) Len() int { return len(p) } func (p runeSlice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }

func reverseString(s string) string { r := runeSlice(s) reverse(r) return string(r) }

var rx = regexp.MustCompile(`\S*`)

func reverseWords(s string) string { return rx.ReplaceAllStringFunc(s, func(m string) string { return reverseString(m) }) }

func reverseWordOrder(s string) string { l := sort.StringSlice(strings.Fields(s)) reverse(l) return strings.Join(l, " ") }

func main() { fmt.Println("Reversed: ", reverseString(phrase)) fmt.Println("Words reversed: ", reverseWords(phrase)) fmt.Println("Word order reversed:", reverseWordOrder(phrase)) }</lang>

Output:

Reversed:            lasrever esarhp edoc attesor
Words reversed:      attesor edoc esarhp lasrever
Word order reversed: reversal phrase code rosetta

Java

Works with: Java version 1.5+

<lang java5>import java.util.Arrays;

public class PhraseRev{ private static String reverse(String x){ return new StringBuilder(x).reverse().toString(); }

private static <T> T[] reverse(T[] x){ T[] rev = Arrays.copyOf(x, x.length); for(int i = x.length - 1; i >= 0; i--){ rev[x.length - 1 - i] = x[i]; } return rev; }

private static String join(String[] arr, String joinStr){ StringBuilder joined = new StringBuilder(); for(int i = 0; i < arr.length; i++){ joined.append(arr[i]); if(i < arr.length - 1) joined.append(joinStr); } return joined.toString(); }

public static void main(String[] args){ String str = "rosetta code phrase reversal";

System.out.println("Straight-up reversed: " + reverse(str)); String[] words = str.split(" "); for(int i = 0; i < words.length; i++){ words[i] = reverse(words[i]); } System.out.println("Reversed words: " + join(words, " ")); System.out.println("Reversed word order: " + join(reverse(str.split(" ")), " ")); } }</lang>

Output:

Straight-up reversed: lasrever esarhp edoc attesor
Reversed words: attesor edoc esarhp lasrever
Reversed word order: reversal phrase code rosetta

jq

Works with: jq version 1.4

<lang jq>def reverse_string: explode | reverse | implode;

"rosetta code phrase reversal" | split(" ") as $words | "0. input: \(.)",

 "1. string reversed:     \(reverse_string)",
 "2. each word reversed:  \($words | map(reverse_string) | join(" "))",
 "3. word-order reversed: \($words | reverse | join(" "))"</lang>

Output:

$ jq -r -n -f Phrase_reversals.jq
0. input:               rosetta code phrase reversal
1. string reversed:     lasrever esarhp edoc attesor
2. each word reversed:  attesor edoc esarhp lasrever
3. word-order reversed: reversal phrase code rosetta

Perl

<lang perl>my $s = "rosetta code phrase reversal"; my $rev_s = reverse($s); my $rev_ew = join(" ", reverse split(/ /,reverse $s)); my $rev_wo = join(" ", reverse split(/ /,$s));

printf "0. %-20s: %s\n", "input", $s; printf "1. %-20s: %s\n", "string reversed", $rev_s; printf "2. %-20s: %s\n", "each word reversed", $rev_ew; printf "3. %-20s: %s\n", "word-order reversed", $rev_wo;</lang>

Output:

0. input               : rosetta code phrase reversal
1. string reversed     : lasrever esarhp edoc attesor
2. each word reversed  : attesor edoc esarhp lasrever
3. word-order reversed : reversal phrase code rosetta

Perl 6

<lang perl6>my $s = 'rosetta code phrase reversal';

say 'Input  : ', $s; say 'String reversed  : ', $s.flip; say 'Each word reversed  : ', $s.words».flip; say 'Word-order reversed : ', $s.words.reverse;</lang>

Output:

Input               : rosetta code phrase reversal
String reversed     : lasrever esarhp edoc attesor
Each word reversed  : attesor edoc esarhp lasrever
Word-order reversed : reversal phrase code rosetta

PHP

This example is incomplete. Shows prompt "Word order reversed:" twice. Please ensure that it meets all task requirements and remove this message.

<lang php><?php // Initialize a variable with the input desired $strin = "rosetta code phrase reversal";

// Show user what original input was echo "Input: ".$strin."\n";

// Show the full input reversed echo "Reversed: ".strrev($strin)."\n";

// reverse the word letters in place $str_words_reversed = ""; $temp = explode(" ", $strin); foreach($temp as $word) $str_words_reversed .= strrev($word)." ";

// Show the reversed words in place echo "Word order reversed: ".$str_words_reversed."\n";

// reverse the word order while leaving the words in order $str_word_order_reversed = ""; $temp = explode(" ", $strin); for($i=(count($temp)-1); $i>=0; $i--) $str_word_order_reversed .= $temp[$i]." ";

// Show the reversal of the word order while leaving the words in order echo "Word order reversed: ".$str_word_order_reversed."\n"; </lang>

Input: rosetta code phrase reversal
Reversed: lasrever esarhp edoc attesor
Word order reversed: attesor edoc esarhp lasrever 
Word order reversed: reversal phrase code rosetta

Python

These examples use the extended slicing notation of [::-1] to reverse strings and lists of strings: <lang python>>>> phrase = "rosetta code phrase reversal" >>> phrase[::-1] # Reversed. 'lasrever esarhp edoc attesor' >>> ' '.join(word[::-1] for word in phrase.split()) # Words reversed. 'attesor edoc esarhp lasrever' >>> ' '.join(word for word in phrase.split()[::-1]) # Word order reversed. 'reversal phrase code rosetta' >>> </lang>

Racket

<lang racket>#lang racket/base (require

 (only-in srfi/13 string-reverse)
 (only-in racket/string string-split string-join))

(define (phrase-reversal s)

 (list
  (string-reverse s)
  (string-join (map string-reverse (string-split s)))
  (string-join (reverse (string-split s)))))

(for-each displayln (phrase-reversal "rosetta code phrase reversal"))</lang>

Output:

lasrever esarhp edoc attesor
attesor edoc esarhp lasrever
reversal phrase code rosetta

Ruby

<lang ruby>str = "rosetta code phrase reversal"

puts str.reverse # Reversed string. puts str.split.map(&:reverse).join(" ") # Words reversed. puts str.split.reverse.join(" ") # Word order reversed.</lang>

Output:

lasrever esarhp edoc attesor
attesor edoc esarhp lasrever
reversal phrase code rosetta

Tcl

<lang tcl>set s "rosetta code phrase reversal"

1. Reverse all characters

puts [string reverse $s]

1. Reverse characters in each word

puts [lmap word $s {string reverse $word}]

1. Reverse the words but not the characters

puts [lreverse $s]</lang>

Output:

lasrever esarhp edoc attesor
attesor edoc esarhp lasrever
reversal phrase code rosetta