How to resolve the algorithm Reverse words in a string step by step in the Pascal programming language

Published on 12 May 2024 09:40 PM
#Pascal

How to resolve the algorithm Reverse words in a string step by step in the Pascal programming language

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Problem Statement

Reverse the order of all tokens in each of a number of strings and display the result;   the order of characters within a token should not be modified.

Hey you, Bub!   would be shown reversed as:   Bub! you, Hey

Tokens are any non-space characters separated by spaces (formally, white-space);   the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input.   Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string   (or one just containing spaces)   would be the result. Display the strings in order   (1st, 2nd, 3rd, ···),   and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.)

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Reverse words in a string step by step in the Pascal programming language

Source code in the pascal programming language

program Reverse_words(Output);
{$H+}

const
  nl = chr(10); // Linefeed
  sp = chr(32); // Space
  TXT =
  '---------- Ice and Fire -----------'+nl+
  nl+
  'fire, in end will world the say Some'+nl+
  'ice. in say Some'+nl+
  'desire of tasted I''ve what From'+nl+
  'fire. favor who those with hold I'+nl+
  nl+
  '... elided paragraph last ...'+nl+
  nl+
  'Frost Robert -----------------------'+nl;

var
  I : integer;
  ew, lw : ansistring;
  c : char;

function addW : ansistring;
var r : ansistring = '';
begin
  r := ew + sp + lw;
  ew := '';
  addW := r
end;

begin
  ew := '';
  lw := '';

  for I := 1 to strlen(TXT) do
  begin
    c := TXT[I];
    case c of
      sp : lw := addW;
      nl : begin writeln(addW); lw := '' end;
      else ew := ew + c
    end;
  end;
  readln;
end.


program reverse_words;
{$mode objfpc}{$h+}
uses
  SysUtils;

function Reverse(a: TStringArray): TStringArray;
var
  I, J: SizeInt;
  t: Pointer;
begin
  I := 0;
  J := High(a);
  while I < J do begin
    t := Pointer(a[I]);
    Pointer(a[I]) := Pointer(a[J]);
    Pointer(a[J]) := t;
    Inc(I);
    Dec(J);
  end;
  Result := a;
end;

const
  Input =
    '---------- Ice and Fire -----------'  + LineEnding +
                                        '' + LineEnding +
    'fire, in end will world the say Some' + LineEnding +
    'ice. in say Some'                     + LineEnding +
    'desire of tasted I''ve what From'     + LineEnding +
    'fire. favor who those with hold I'    + LineEnding +
                                        '' + LineEnding +
    '... elided paragraph last ...'        + LineEnding +
                                        '' + LineEnding +
    'Frost Robert -----------------------' + LineEnding;
var
  Line: string;

begin
  for Line in Input.Split([LineEnding], TStringSplitOptions.ExcludeLastEmpty) do
    WriteLn(string.Join(' ', Reverse(Line.Split([' ']))));
end.

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