How do I remove blank lines from text in PHP?

Question

I need to remove blank lines (with whitespace or absolutely blank) in PHP. I use this regular expression, but it does not work:

$str = ereg_replace('^[ \t]*$\r?\n', '', $str);
$str = preg_replace('^[ \t]*$\r?\n', '', $str);

i want result of:

blahblah

blahblah

   adsa 


sad asdasd

will:

blahblah
blahblah
   adsa 
sad asdasd

Answer 1

what about this?

$str = preg_replace('^\s+\r?\n$', '', $str);

Answer 2

preg_replace("/(^[\r\n]*|[\r\n]+)[\s\t]*[\r\n]+/", "", $string);

Answer 3

$str = preg_replace('/^[ \t]*[\r\n]+/m', '', $str);