regular expressions - enclosed in single or double quotation marks?

[dr0n3]

When using functions such as ereg() and ereg_replace(), should I use single or double quotation marks to enclose the regular expression?

Example:

ereg('regular expression',$string)

OR

ereg("regular expression",$string)

I have no idea which of the two I should be using because it varies in the documentation.

[Frederick]

it really doesn't matter wich one you use, just have to be consistent through the function of which one is used.

ereg_replace("blahblah","blah",$str);

ereg_replace('blahblah','blah',$str);

I use double quotes because they stand out more for troubleshooting the code. Single quotes sometimes blend in with other characters within your code. But, sometimes you must use single quotes as with queries.

[dr0n3]

I have been using single quotation marks to enclose my regular expressions, however, I have come across instances where I cannot use single quotes, for example:

ereg_replace("\n{2,}","\n\n",$_POST['message']) // Replace 2 or more line feeds with a single line feed.

I have to use double quotation marks or else \n is taken literally.