Regex 101 Exercise I8 - replace space count with spaces

Exercise I8 - replace space count with spaces

Given a string with embedded space counts:

<15sp>Indented by 15 spaces

Replace the <<count>sp> with <count> spaces.

So, if you have

<4sp>Text

you should end up with

    Text

Comments

• Anonymous
  February 13, 2006
  using System;
  using System.Text.RegularExpressions;
  
  class Rx
  {
         public static void Main(string[] args)
         {
                 string text = "<8sp>hello<1sp>world";
                 string[] ar = Regex.Split(text, "<([0-9]?)sp>");
                 text = "";
                 for(int i=1; i<ar.Length; i=i+2)
                 {
                         text+=spaces(int.Parse(ar[i]))+ar[i+1];
                 }
                 Console.WriteLine(text);
         }
         static string spaces(int s)
         {
                 string foo = "";
                 while(s-->0)
                 {
                         foo += " ";
                 }
                 return foo;
         }
  }
  
  
  Output:
  jozjan@black:~/temp$ mcs rx.cs
  jozjan@black:~/temp$ ./rx.exe
         hello world
  
  
  Other ideas?

• Anonymous
  February 13, 2006
  A slightly different approach:
  
  using System;
  using System.Text.RegularExpressions;
  
  
  class RegExample
  {
  
  [STAThread]
  static void Main(string[] args)
  {
  RegExample rex = new RegExample();
  string text = "<10sp>Hello,<1sp>World!<2sp>With<1sp>Regular<1sp>Expressions!";
  MatchEvaluator myEvaluator = new MatchEvaluator(rex.spaces);
  Console.WriteLine(Regex.Replace(text,"<([0-9])*sp>", myEvaluator));
  }
  
  public string spaces(Match m)
  {
  string tmp = "";
  int i= Convert.ToInt32(m.Value.Split("<sp>".ToCharArray())[1]);
  for(int x=0;x<i;++x)
  {
  tmp += " ";
  }
  return tmp;
  }
  
  }
  
  
  output:
  
  >RegExample.exe
           Hello, World!  With Regular Expressions!
  

• Anonymous
  February 13, 2006
  using System;
  using System.Text;
  using System.Text.RegularExpressions;
  
  class RegExSample
  {
  static string ExpandSpaces(string s)
  {
  string pattern =
  @"
  < # start of tag
  (d+) # one or more digits
  sp # literal 'sp'
  > # end of tag
  ";
  
  return Regex.Replace(
  s,
  pattern,
  new MatchEvaluator(
  RegExSample.ExpandSpacesByMatch
  ),
  RegexOptions.IgnorePatternWhitespace
  );
  }
  
  static string ExpandSpacesByMatch(Match m)
  {
  string sCount = m.Groups[1].ToString();
  int iCount = int.Parse(sCount);
  string s = new string(' ', iCount);
  return s;
  }
  
  static void Main(string[] args)
  {
  if (args.Length == 0)
  {
  run("a<1sp>b");
  }
  foreach (string s in args)
  {
  run(s);
  }
  }
  
  static void run(string s)
  {
  System.Console.WriteLine();
  System.Console.WriteLine("original: "" + s + """);
  System.Console.WriteLine("modified: "" + ExpandSpaces(s) + """);
  }
  }
  
  >RegExSample "a<1sp>b<2sp>c" "a<15sp>"
  
  original: "a<1sp>b<2sp>c"
  modified: "a b  c"
  
  original: "a<15sp>"
  modified: "a               "

• Anonymous
  February 13, 2006
  Using the interpolation module from http://search.cpan.org/~jenda/Interpolation-0.70.1/Interpolation.pm
  
  perl -pe "use Interpolation n => sub { ' ' x $_[0] }; s/<sp[>]/$n{$1}/g"
  
  Yay for Perl.

• Anonymous
  February 13, 2006
  Grrr... indentation is left as an exercise.

• Anonymous
  February 13, 2006
  Or just use /e :)
  
  perl -e "$_ = shift; s/<(d+)sp>/' ' x $1/eg; print;" "a<1sp>b<2sp>c"

• Anonymous
  February 13, 2006
  Or if you don't like /e there's eval-by-anonymous-array-inclusion:
  perl -e "$_ = shift; s/<(d+)sp>/@{ [ ' ' x $1 ] }/g; print;" "a<0sp>b<1sp>c<2sp>d"
  
  Or even
  perl -e "$_ = shift; s/<(d+)sp>/@{ [ map { ' ' } (1 .. $1) ] }/g; print;" "a<0sp>b<1sp>c<2sp>d"
  
  (Yuck...)

• Anonymous
  February 13, 2006
  Indented version of C# above:
  http://www.geocities.com/mvaneerde/expand-spaces.txt

• Anonymous
  February 13, 2006
  Woah, /e is cool.
  
  perl -pe "s/<(d+)sp>/' 'x$1/eg"

• Anonymous
  February 13, 2006
  I think that Maurits' answer(s) covers it.  I couldn't come up with a more succinct way of writing it.

• Anonymous
  February 14, 2006
  Regex regex = new Regex(@"<(d+)sp>", RegexOptions.Compiled | RegexOptions.IgnoreCase);
             Console.WriteLine("Type in the HTML text you want to process:");
             String inputHtml = Console.ReadLine();
             String resultHtml = regex.Replace(inputHtml, delegate(Match match)
             {
                 return new String(' ', Int32.Parse(match.Groups[1].Value));
             });
  So far, mine is the shortest one, so far so good:-)
  
  Sheva

• Anonymous
  February 14, 2006
  TrackBack From:http://sheva.cnblogs.com/archive/2006/02/15/331343.html

• Anonymous
  February 15, 2006
  TrackBack From:http://sheva.cnblogs.com/archive/0001/01/01/331343.html

• Anonymous
  February 24, 2006
  No official answer?

• Anonymous
  June 02, 2009
  PingBack from http://woodtvstand.info/story.php?id=85632

• Anonymous
  June 07, 2009
  PingBack from http://greenteafatburner.info/story.php?id=2270