Convert/replace U+2009 character with space

I have a string that contains unreadable space character:

How can I replace this character with a normal space so I can get a string like: "a b c d"

I have tried this:

$str = utf8_decode($str);

But it converts that character to question mark ?

>Solution :

Try to replace using preg match –

$string = "   test   string and XY \t ";

$trimString = trim(preg_replace('/[\pZ\pC]/u', ' ', $string));
//test\x20\x20\x20string\x20and\x20XY

Details

• ^[\pZ\pC]+ – one or more whitespace or control chars at the start of string

• | – or
  [\pZ\pC]+$ – one or more whitespace or control chars at the end of string

• | – or
  (?! )[\pZ\pC] – one or more whitespace or control chars other than a regular space anywhere inside the string

• [^\S ] – any whitespace other than a regular space (\x20)