How many characters are visible like a space, but are not a space characters?

Question

If I want to discover the hexadecimal equivalent of a space in PHP I can play with bin2hex:

php > echo var_dump(bin2hex(" "));
string(2) "20"

I can also obtain space character from "20"

php > echo var_dump(hex2bin("20"));
string(1) " "

But there exist Unicode versions of a "visible" space:

php > echo var_dump(hex2bin('c2a0'));
string(2) " "

So, I can get some string (for example from HTTP requests) where I cannot recognize the "no break space" with my eyes. So, ...

$string = preg_replace('~\x{00a0}~siu', ' ', $string);

Is there a better way to find and replace all "space like" characters in PHP?

Answer 1

You can make use of a Unicode category \p{Zs}:

Zs    Space separator

$string = preg_replace('~\p{Zs}~u', ' ', $string);

The \p{Zs} Unicode category class will match these space-like symbols:

Character   Name
U+0020      SPACE
U+00A0      NO-BREAK SPACE
U+1680      OGHAM SPACE MARK
U+2000      EN QUAD
U+2001      EM QUAD
U+2002      EN SPACE
U+2003      EM SPACE
U+2004      THREE-PER-EM SPACE
U+2005      FOUR-PER-EM SPACE
U+2006      SIX-PER-EM SPACE
U+2007      FIGURE SPACE
U+2008      PUNCTUATION SPACE
U+2009      THIN SPACE
U+200A      HAIR SPACE
U+202F      NARROW NO-BREAK SPACE
U+205F      MEDIUM MATHEMATICAL SPACE
U+3000      IDEOGRAPHIC SPACE