Advice please on stripping non-printing characters

[J Taylor]

Hi!

I've seen various examples of stripping non-printing (and non-ascii)
chars from a string with something like this:

$string =~ s/[\000-\037]/ /g;

I've chosen to strip all but the printable ascii chars (using hex):

$string =~ s/[^\x20-\x7f]/ /g;

This *seems* to work better for my purposes, I'm wondering though if are
gotchas I'm missing.

Thanks.

 

[Anno Siegel]

Hi!

I've seen various examples of stripping non-printing (and non-ascii)
chars from a string with something like this:

$string =~ s/[\000-\037]/ /g;

If you're going to use explicit character codes, you might as well use

$string =~ tr/\0-\037/ /; # untested

I've chosen to strip all but the printable ascii chars (using hex):

$string =~ s/[^\x20-\x7f]/ /g;

$string =~ tr/\x20-\x7f/ /c;

This *seems* to work better for my purposes, I'm wondering though if are
gotchas I'm missing.

What gotchas? The difference is obvious, and if that's what you want
"nonprinting character" to mean, who's going to stop you?

The approach has the disadvantage that it is hard to adapt to non-ascii
alphabets. POSIX character classes are locale-sensitive, so

$string =~ s/[[rint:]]/ /g;

has better chances. There is also a Unicode equivalent (see perlre).

Anno

 

[Ilmari Karonen]

I've chosen to strip all but the printable ascii chars (using hex):

$string =~ s/[^\x20-\x7f]/ /g;

This *seems* to work better for my purposes, I'm wondering though if are
gotchas I'm missing.

"\x7f" is not printable.