3v4l.org

run code in 300+ PHP versions simultaneously
<?php $strs = ['2 + 2', 'f( " ")', 'f("Test \\"mystring\\" .")', 'f("\' ", " ")']; $rx = '~(?<!\\\\)(?:\\\\{2})*(?:"[^\\\\"]*(?:\\\\.[^"\\\\]*)*"|\'[^\'\\\\]*(?:\\\\.[^\'\\\\]*)*\')(*SKIP)(*F)|\h+~s'; print_r( preg_replace($rx, '', $strs) );
Output for 7.1.25 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
Array ( [0] => 2+2 [1] => f(" ") [2] => f("Test \"mystring\" .") [3] => f("' "," ") )
preferences:
116.67 ms | 1507 KiB | 4 Q