Replace excess whitespaces and line-breaks with PHP?

Question

$string = "My    text       has so    much   whitespace         Plenty of    spaces  and            tabs";  echo preg_replace("/\s\s+/", " ", $string); 

I read the PHP's documentation and follow the preg_replace's tutorial, however this code produce

My text has so much whitespace Plenty of spaces and tabs

How can I turn it into :

My text has so much whitespace
Plenty of spaces and tabs

Answer 1

First, I'd like to point out that new lines can be either \r, \n, or \r\n depending on the operating system.

My solution:

echo preg_replace('/[ \t]+/', ' ', preg_replace('/[\r\n]+/', "\n", $string)); 

Which could be separated into 2 lines if necessary:

$string = preg_replace('/[\r\n]+/', "\n", $string); echo preg_replace('/[ \t]+/', ' ', $string); 

Update:

An even better solutions would be this one:

echo preg_replace('/[ \t]+/', ' ', preg_replace('/\s*$^\s*/m', "\n", $string)); 

Or:

$string = preg_replace('/\s*$^\s*/m', "\n", $string); echo preg_replace('/[ \t]+/', ' ', $string); 

I've changed the regular expression that makes multiple lines breaks into a single better. It uses the "m" modifier (which makes ^ and $ match the start and end of new lines) and removes any \s (space, tab, new line, line break) characters that are a the end of a string and the beginning of the next. This solve the problem of empty lines that have nothing but spaces. With my previous example, if a line was filled with spaces, it would have skipped an extra line.