DaniWeb Forum Index > Web Development > PHP

how to remove space from string?

Please support our PHP advertiser: $6.99 Domain Names at 1&1. Includes Free Privacy. Save Now!

•

Join Date: Nov 2007

Posts: 3,833

Reputation: nav33n is a jewel in the rough

Solved Threads: 344

nav33n

Offline

Senior Poster

Re: how to remove space from string?

#11

Mar 13th, 2009

•

Originally Posted by mschroeder

GAH! Just realized how old this thread is, how did it get resurrected?!

Someone read the Book of the dead I suppose !

Ignorance is definitely not bliss!

*PM asking for help will be ignored*

•

Join Date: Jul 2008

Posts: 151

Reputation: mschroeder is on a distinguished road

Solved Threads: 25

mschroeder mschroeder is offline

Offline

Junior Poster

Re: how to remove space from string?

#12

Mar 13th, 2009

•

Originally Posted by terry.b

Thanks. Very elegant solution. Wish you were around when this question was originally posted.

Oh, and btw, please forgive my ignorance. Like all people who reinvent the so-called wheel, I didn't know it existed. Thanks for the enlightenment.

If it solves your problem how you need it to solve your problem then its a solution. There is always more than one way to skin a cat.

If you're question/problem is solved don't forget to mark the thread as Solved!

-- Code I post is usually but not always tested. If it is tested it will be against 5.2.12 or 5.3.1

•

Join Date: Sep 2005

Posts: 1,110

Reputation: digital-ether is just really nice

Solved Threads: 68

digital-ether digital-ether is offline

Offline

Veteran Poster

Re: how to remove space from string?

#13

Mar 15th, 2009

Just to clear things up:

•

Is there php function to remove the space inside the string? for example:
$abcd="this is a test"
I want to get the string:
$abcd="thisisatest"

How to do that? thanks.

str_replace() will remove *all* occurrence of whitespace.

 Help with Code Tags 
 PHP Syntax (Toggle Plain Text) 
$str = str_replace(' ', '', $str);
$str = str_replace(' ', '', $str);

So it solves the problem in the original post.

The post:

•

Try this:
NOTE: this actually leaves one space between words. If you move the
$newstr = $newstr . substr($s, $i, 1);
after the while loop it will strip all spaces as you wanted.

function StripExtraSpace($s)
{
for($i = 0; $i < strlen($s); $i++)
{
$newstr = $newstr . substr($s, $i, 1);
if(substr($s, $i, 1) == ' ')
while(substr($s, $i + 1, 1) == ' ')
$i++;
}
return $newstr;
}

Offers a solution that removes excess whitespace.

So if you want to turn:

Help with Code Tags

PHP Syntax (Toggle Plain Text)

$str = "this     is      a     string     with      excess     whitespace";

into:

Help with Code Tags

PHP Syntax (Toggle Plain Text)

"this is a string with excess whitespace";

You could use the StripExtraSpace() function provided above.

•

Originally Posted by mschroeder

For starters, functions in loops should be avoided whenever possible. e.g. for($i = 0; $i < strlen($s); $i++) also, you're doing a lot of extra work here.

I would suggest something like this:
Help with Code Tags

php Syntax (Toggle Plain Text)
<?php
 
$sTestString = 'This  is a stringwith    lots of 	odd spaces and tabs		
and some newlines too
 
lets see if this works.';
 
$sPattern = '/\s*/m'; 
$sReplace = '';
 
echo $sTestString . '<br />';
echo preg_replace( $sPattern, $sReplace, $sTestString );
<?php $sTestString = 'This is a stringwith lots of odd spaces and tabs and some newlines too lets see if this works.'; $sPattern = '/\s*/m'; $sReplace = ''; echo $sTestString . '<br />'; echo preg_replace( $sPattern, $sReplace, $sTestString );
Regular Expression removes ALL whitespace ( spaces, tabs, newlines) 0 or more times and also traverses multiple lines.

Put that in a file and run it in your browser, view the source and you'll see exactly what it has done.

No need to reinvent the wheel.

Regex is really slow, I mean really really slow. So even a loop is likely to be faster.

I benchmarked the regex function and StripExtraSpace(). The regex function is twice as fast. However, an optimized version of StripExtraSpace() is faster then the regular expression.

 Help with Code Tags 
 PHP Syntax (Toggle Plain Text) 
function loopStripExtraWhitespaceOptimized($str) {
	$len = strlen($str);
	for($i = 0; $i < $len; $i++) {
		$newstr .= $str[$i];
		while($str[$i] == ' ') {
			$i++;
		}
	}
	return $newstr;
}
function loopStripExtraWhitespaceOptimized($str) {
	$len = strlen($str);
	for($i = 0; $i < $len; $i++) {
		$newstr .= $str[$i];
		while($str[$i] == ' ') {
			$i++;
		}
	}
	return $newstr;
}

Note the if/else is removed as this is implied in the while() loop. Also using the string's built in array index is a lot faster then substr().

The computational/time complexity of a regular expression is quite high. So an O(n), where n is the length of the string, such as the above can be just as fast, or faster.

Using a native PHP string function can speed things up:

 Help with Code Tags 
 PHP Syntax (Toggle Plain Text) 
function stripExtraWhitespace($str) {
	while($str != ($_str = str_replace('  ', ' ', $str))) {
		$str = $_str;
	}
	return $str;
}
function stripExtraWhitespace($str) {
	while($str != ($_str = str_replace('  ', ' ', $str))) {
		$str = $_str;
	}
	return $str;
}

This is about 30x faster the above two. This has a worst case O(log 2 n), but realistically it would be just 2-3 operations of str_replace().

Here is the benchmarks:

 Help with Code Tags 
 PHP Syntax (Toggle Plain Text) 
<?php
 
function strStripWhitespace($str) {
	return str_replace(' ', '', $str);
}
 
function regexStripExtraWhitespace($str) {
	return preg_replace('/\s*/m', ' ', $str);
}
 
function loopStripExtraWhitespace($str) {
	$len = strlen($str);
	for($i = 0; $i < $len; $i++) {
		$newstr .= substr($str, $i, 1);
		while(substr($str, $i + 1, 1) == ' ') {
			$i++;
		}
	}
	return $newstr;
}
 
function loopStripExtraWhitespaceOptimized($str) {
	$len = strlen($str);
	for($i = 0; $i < $len; $i++) {
		$newstr .= $str[$i];
		while($str[$i] == ' ') {
			$i++;
		}
	}
	return $newstr;
}
 
function loopStripExtraWhitespace2($str) {
	while($str != ($_str = str_replace('  ', ' ', $str))) {
		$str = $_str;
	}
	return $str;
}
 
function benchMark($function, $arg = null, $loops = 1000) {
	$start = microtime(1);
	for($i = 0; $i < $loops; $i++) {
		$function($arg);
	}
	return microtime(1)-$start;
}
 
ini_set('max_execution_time', 0);
 
$str = "\t hello    this is a   string.\r\n";
for($i = 0; $i < 10; $i++) {
	$str .= $str;
}
 
echo benchMark('strStripWhitespace', $str, 1000);
echo '<br />';
echo benchMark('regexStripExtraWhitespace', $str, 1000);
echo '<br />';
echo benchMark('loopStripExtraWhitespace', $str, 1000);
echo '<br />';
echo benchMark('loopStripExtraWhitespaceOptimized', $str, 1000);
echo '<br />';
echo benchMark('loopStripExtraWhitespace2', $str, 1000);
echo '<br />';
 
?>
<?php

function strStripWhitespace($str) {
	return str_replace(' ', '', $str);
}

function regexStripExtraWhitespace($str) {
	return preg_replace('/\s*/m', ' ', $str);
}

function loopStripExtraWhitespace($str) {
	$len = strlen($str);
	for($i = 0; $i < $len; $i++) {
		$newstr .= substr($str, $i, 1);
		while(substr($str, $i + 1, 1) == ' ') {
			$i++;
		}
	}
	return $newstr;
}

function loopStripExtraWhitespaceOptimized($str) {
	$len = strlen($str);
	for($i = 0; $i < $len; $i++) {
		$newstr .= $str[$i];
		while($str[$i] == ' ') {
			$i++;
		}
	}
	return $newstr;
}

function loopStripExtraWhitespace2($str) {
	while($str != ($_str = str_replace('  ', ' ', $str))) {
		$str = $_str;
	}
	return $str;
}

function benchMark($function, $arg = null, $loops = 1000) {
	$start = microtime(1);
	for($i = 0; $i < $loops; $i++) {
		$function($arg);
	}
	return microtime(1)-$start;
}

ini_set('max_execution_time', 0);

$str = "\t hello    this is a   string.\r\n";
for($i = 0; $i < 10; $i++) {
	$str .= $str;
}

echo benchMark('strStripWhitespace', $str, 1000);
echo '<br />';
echo benchMark('regexStripExtraWhitespace', $str, 1000);
echo '<br />';
echo benchMark('loopStripExtraWhitespace', $str, 1000);
echo '<br />';
echo benchMark('loopStripExtraWhitespaceOptimized', $str, 1000);
echo '<br />';
echo benchMark('loopStripExtraWhitespace2', $str, 1000);
echo '<br />';

?>

www.fijiwebdesign.com - web design and development and fun
Cpanel Email - Let users Register email accounts on your website upon registration
Ajax Chat - Fully browser based chat!

•

Join Date: Jul 2008

Posts: 151

Reputation: mschroeder is on a distinguished road

Solved Threads: 25

mschroeder mschroeder is offline

Offline

Junior Poster

Re: how to remove space from string?

#14

Mar 15th, 2009

Well you're definitely right. regex is definitely slower when compared to str_replace especially as the length of the string increases. Although return str_replace(' ', '', $str); is not the same as return preg_replace('/\s*/m', ' ', $str); as the regex covers ALL whitespace, newlines tabs etc etc. When i ran your benchmarks on 5.3b1 str_replace did not replace tabs and new lines in the output.

However adding those to an array of replacements in str_replace still drastically spanked the regular expression replacement.

I feel kinda stupid for overlooking to most obvious solution to a few year old thread haha.

If you're question/problem is solved don't forget to mark the thread as Solved!

-- Code I post is usually but not always tested. If it is tested it will be against 5.2.12 or 5.3.1

•

Join Date: Sep 2005

Posts: 1,110

Reputation: digital-ether is just really nice

Solved Threads: 68

digital-ether digital-ether is offline

Offline

Veteran Poster

Re: how to remove space from string?

#15

Mar 16th, 2009

•

Originally Posted by mschroeder

Well you're definitely right. regex is definitely slower when compared to str_replace especially as the length of the string increases. Although return str_replace(' ', '', $str); is not the same as return preg_replace('/\s*/m', ' ', $str); as the regex covers ALL whitespace, newlines tabs etc etc. When i ran your benchmarks on 5.3b1 str_replace did not replace tabs and new lines in the output.

However adding those to an array of replacements in str_replace still drastically spanked the regular expression replacement.

I feel kinda stupid for overlooking to most obvious solution to a few year old thread haha.

Good spotting that one. Yes, it would still be faster with an array of replacements, and even faster if you just did removal of newlines and tabs once outside the function as it doesn't need multiple passes. Only the spaces need multiple passes.

www.fijiwebdesign.com - web design and development and fun
Cpanel Email - Let users Register email accounts on your website upon registration
Ajax Chat - Fully browser based chat!

•

Join Date: Jun 2009

Posts: 30

Reputation: elamigosam is an unknown quantity at this point

Solved Threads: 1

elamigosam elamigosam is offline

Offline

Light Poster

Re: how to remove space from string?

#16

Jun 12th, 2009

hi I am new here, but I am interested in using that code and I have a question.

I can input a variable, but how can i get the result from it "with no spaces" and put it in a variable, like $nospacename

•

Join Date: Dec 2009

Posts: 1

Reputation: sridharkalabala is an unknown quantity at this point

Solved Threads: 0

sridharkalabala sridharkalabala is offline

Offline

Newbie Poster

Simple way.....!

-1

#17

Dec 6th, 2009

$str=" Your string

with lines

"
$str=str_replace (" ", "", trim($str));

•

Join Date: Feb 2004

Posts: 10,496

Reputation: crunchie is a splendid one to behold

Solved Threads: 805

crunchie

Offline

Spyware Killer

#18

Dec 6th, 2009

This thread is dead folks. Take a look at the last post date.

Proud member of ASAP (Alliance of Security analysis Professionals).
Opera AVAST anti-virus Comodo AV/Firewall Spywareblaster

•

Join Date: Aug 2007

Posts: 163

Reputation: hemgoyal_1990 is an unknown quantity at this point

Solved Threads: 11

hemgoyal_1990 hemgoyal_1990 is offline

Offline

Junior Poster

-1

#19

Dec 6th, 2009

use below script:

 Help with Code Tags 
 PHP Syntax (Toggle Plain Text) 
$string = "This is a test.";
 
$new_string = str_replace (" ", "", $string);
 
echo "$new_string";
$string = "This is a test.";

$new_string = str_replace (" ", "", $string);

echo "$new_string";