Parsing Text

onewaydom · October 9, 2007

Hello,

I am new to regular expressions.

Problem:

1. Remove all text before a certain string.

2. Replace something in the beginning string.

3. Replace something in the end of a string.

4. Be able to add a break after the end of each string.

5. Have this work on long strings repeating itself.

Example:

Dealing with large text files as long directories.

i.e. onebiglongdirectory/prefix/somethingelsehere/suffix

onebiglongdirectory/prefix/somethingelsehere/suffix

Of course with space and other unnecessary text also included.

Solution:

1. I would like everything before the prefix dropped and replaced with a value that I input into a variable.

2. I would like the suffix dropped and replaced with a variable that I input as a variable.

3. Each directory on its own line.

Here is something I have created. It works a bit, but stops short of doing the whole string of directories I put into it.

index.php

<html>

<head>

</head>

<body bgcolor = "#ACACAC">

<center>

<h1>Regular Expressions Engine</h1>

<h5>Enter the prefix that is to be changed along with the suffix, both new and old.</h5>

<form method=post action="expressions.php">

New Prefix 
<input type=text name="newprefix" size=40 style="background:#ECECEC"><br><br>

Old Prefix
<input type=text name="oldprefix" size=40 style="background:#ECECEC"><br><br>

New Suffix
<input type=text name="newsuffix" size=40 style="background:#ECECEC"><br><br>

Old Suffix

<input type=text name="oldsuffix" size=40 style="background:#ECECEC"><br><br>


Enter the string to be manipulated:<br><br>

<textarea name="content" rows=6 cols=40 style="background:#FFFDDA">

</textarea>

<br><br>

<input type=submit value="Process">  <input type="reset" value="Reset">

</form>

</center>

</body>
</html>

expressions.php

<?

  $content = trim( "$content"); 

  $firststring =strstr("$content", "$oldprefix");
  
  $string= str_replace("$oldprefix","$newprefix",$firststring);

  $second = str_replace("$oldsuffix","$newsuffix <br>",$string);


?>

    <html>
      <title>Regular Expressions Results</title>
         <body bgcolor = "#ACACAC">

           <center>
             <h1>Results</h1>

              <p><br><b></b></p>

              <p>

                <b><font color="#00A54E">

         <? 
            echo $second;
          ?> 
       </b></font>

</p>
<br>
<br>
<br>

<a href ="http://www.mydomain.com/regex">Back</a>

</center>

</body>
</html>

Any help appreciated. I know the expressions I am looking for, but just don't know how to get them into php.

Replace oldsuffix to the end of the line with newsuffix

\.oldsuffix.*$ .newsuffix

Replace beginning of the line up to and including /oldprefix with /newprefix

^.*?/oldprefix

Hope this makes sense!

Thanks

effigy · October 9, 2007

1. Remove all text before a certain string.

2. Replace something in the beginning string.

3. Replace something in the end of a string.

4. Be able to add a break after the end of each string.

5. Have this work on long strings repeating itself.

1. /\A(.*?)(?=string)/s

2. /\Apattern/

3. /pattern\z/

4. /\s*\z/ replaced with a new line.

5. A string containing multiple lines?

onewaydom · October 9, 2007

5. A string containing multiple lines?

A long list of data that needs to be adjusted.

effigy · October 9, 2007

That sounds like the same thing to me, unless you're looping through a file line by line rather than slurping it all into one string. In either case, you're still using preg_replace.

onewaydom · October 9, 2007

How would I setup 'preg_replace'?

effigy · October 9, 2007

preg_replace

onewaydom · October 9, 2007

BIG HELP

onewaydom · October 9, 2007

That sounds like the same thing to me, unless you're looping through a file line by line rather than slurping it all into one string. In either case, you're still using preg_replace.

I have the initial prefix and suffix being adjusted properly, but when I have more than one occurrence the function only takes care of the beginning and the end.

 $second = preg_replace(" /\A(.*?)($oldprefix?)/s", "$newprefix", "$content");
$third = preg_replace(" /$oldsuffix\z/", "$newsuffix", "$second");

I would like it to make a new line after each new suffix is added. Additionally be able to do multiple lines of similar, but different text. A long list if you will.

effigy · October 9, 2007

In order to handle multiple lines, change \A to ^, and add the /m modifier at the end, e.g. /^(.*?)($oldprefix)/sm. Keep in mind that if you use a variable within a regular expressions, it must first be passed through preg_quote.

onewaydom · October 9, 2007

Not sure if this is what you were meaning, but this works.

  $content = trim( "$content"); 

  $oldprefix = preg_quote($oldprefix, '/');

  $second = preg_replace(" /^(.*?)($oldprefix?)/sm", "$newprefix", "$content");
  
  $third= str_replace("$oldprefix","$newprefix",$second);

  $fourth = str_replace("$oldsuffix","$newsuffix <br>",$third);

effigy · October 9, 2007

Why are you using ? after $oldprefix?

FYI: You don't have to double quotes variable names unless they're being combined with other literals or strings.

onewaydom · October 10, 2007

Cool, thank you for the info. I have something very useful now!

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Parsing Text

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