Regex to find ampersands without spaces on both sides

Question

I'm just trying to figure out the regex to find any ampersands that aren't immediately preceded and followed by a space. For example, it would find "asdf&asdf" and "asdf& asdf" but not "asdf & asdf"

This will be used in a preg_replace to add spaces before and after. (If you're wondering, the problem is that I'm stuck with a WYSIWYG that has a bug where it strips spaces on both sides of ampersands, and I need to manually add them back after the fact). Thoughts?

Answer 1

To put space if it is not there on either side, can be done like this

echo preg_replace('/ ?& ?/',' & ','asdf&asdf asdf& asdf asdf & asdf');
//asdf & asdf asdf & asdf asdf & asdf

For without spaces on both sides (Answering to question title), it will fail on asdf& asdf

echo preg_replace('/(?<! )&(?! )/',' & ','asdf&asdf asdf& asdf asdf & asdf');
//asdf & asdf asdf& asdf asdf & asdf

Answer 2

Ampersand with non-space after or before:

(&[^ ]|[^ ]&)

Answer 3

([^\s]+&.+)|(.+&[^\s]+)

This regex makes sure that there is no space on the left xor the right of an & character

Answer 4

(\S&\S|\s&\S|\S&\s)

• Non whitespace char, followed by & and another non space char
  OR
• Whitespace followed by &, followed by non space char
  OR
• Non whitespace char followed by &, followed by another whitespace char

Answer 5

Ampersand width not after a space or ampersand not before a space, but not both:

(?<!\s)&|&(?!\s)

Using lookaround, so this captures the ampersand only.

Answer 6

I suggest to first find all ampersands independent of the characters to the left and right and then use a negative look behind assertion to ensure that not both characters are spaces.

.&.(?<! & )

Answer 7

It should work (not tested) : /([^\s]&|&[^\s])/. If you are only concerned about spaces and not "any blank character" : /([^ ]&|&[^ ])/