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change multiple spaces to one space - php

Hi

This follows on my previous question here:
http://tinyurl.com/35k9wnq 

I need to replace random number of spaces in each line with one space so that a line like this:
192\.168\.99\.44            25h/day
becomes
192\.168\.99\.44 25h/day.

I am reading the lines into an array with this script:

<?PHP
   $file_handle = fopen("/var/squish/squish.conf", "rb");
     while (!feof($file_handle) ) {
       $line_of_text = fgets($file_handle);
       if (substr($line_of_text,0,1)!='#') {
         $parts = explode(' ', $line_of_text);
         print $parts[0] . $parts[1]. "<BR>";
         }
  }
fclose($file_handle);
?>

and because I am splitting the lines with a space the random numbers make things go haywire.
0
QuintusSmit
Asked:
QuintusSmit
3 Solutions
 
mcuk_stormCommented:
You can use preg_replace to use a regular expression to match one or more spaces and replace them with one:
$result = preg_replace("/[ ]+/"," ",$subject);
0
 
zappafan2k2Commented:
The PHP file function reads a file into an array based on line breaks for you.

Here's how I would do it.

<?php
$myArray = file("/var/squish/squish.conf");
foreach ($myArray as $line) {
  $line = preg_replace('/\s+/', ' ', $line);
  if (!preg_match('/^#/', $line) {
    $parts = preg_split('/ /', $line);
    echo implode('<whateverdelimiteryouwant>', $parts) ."<br>";
    }
  }
?>

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0
 
Rok-KraljCommented:
Regular expressions are terribly slow.

use staigforward solution.

$n will be the new string.

$c=file_get_contents('/var/squish/squish.conf');
$n='';

$prev=false;
$size=strlen($c);
for($i=0; $i<$size; ++$i) {
	if ($c[$i]==' ') {
		if (!$prev) {
			$prev=true;
			$n.=' ';
		}
	} else {
		$n.=$c[$i];
		$prev=false;
	}
}

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mcuk_stormCommented:
I don't think you do regexp's justice, I have just compared the following two script:

1:
<?php
$c=file_get_contents('testdata');
$n='';

$prev=false;
$size=strlen($c);
for($i=0; $i<$size; ++$i) {
        if ($c[$i]==' ') {
                if (!$prev) {
                        $prev=true;
                        $n.=' ';
                }
        } else {
                $n.=$c[$i];
                $prev=false;
        }
}
echo $n;
?>


2:
<?php

$n='';
$data = file('testdata');
foreach($data as $line) {
        $n .= preg_replace('/[ ]+/',' ',$line);
}
echo $n;
?>


Script 1 execution:
time php < test.php | md5sum
989438e5c3647807a7b552c7212515c4  -

real    0m22.861s
user    0m22.378s
sys     0m0.164s


Script 2 execution:
time php < regexp.php | md5sum  
989438e5c3647807a7b552c7212515c4  -

real    0m0.317s
user    0m0.208s
sys     0m0.105s


The test dataset was a 10000 row file, each row containing two segments of data separated by the same number of spaces as the record number. To rule out the difference between file and file_get_contents i ran tests with just these statements in and file is about 0.1sec slower than get_contents. The MD5s show that the outputs are the same
0
 
Ray PaseurCommented:
REGEX is the correct way to do this.  "Slow" is irrelevant in the instant context.  You would need to do hundreds of millions of REGEX before you could even notice a difference, and the time spent on this question will never be recovered in "real life."

Please see example #5 of the man page here:
http://us2.php.net/manual/en/function.preg-replace.php

We have that example in the PHP/net web site because it's the right way to do it! ~Ray
Example #5 Strip whitespace

This example strips excess whitespace from a string.
<?php
$str = 'foo   o';
$str = preg_replace('/\s\s+/', ' ', $str);
// This will be 'foo o' now
echo $str;

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0
 
Rok-KraljCommented:
@mcuk_storm:

Hm, that is probably the reason because regex module is written in C and can execute machine code directly, but generally, my approach is faster.

My mistake, I guess that is my C++ stereotype that isn't true for PHP.
0
 
mcuk_stormCommented:
@Rok-Kralj
Regexp can be very inefficient depending on the complexity of the statements and how they are written (though usually the alternative code is just as complex) but for smaller statements it is generally pretty well optimised. Unfortunately it does seem to have the stigma of being slow but its not always the case.
0
 
QuintusSmitAuthor Commented:
tx for all the responses - regular expressions would be fine as this file will never have more than 150 lines
0
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