More than 9 backreferences in gsub()

Question

How to use gsub with more than 9 backreferences? I would expect the output in the example below to be \"e, g, i, j, o\".

> test <- \"abcdefghijklmnop\"
&g         


        

Answer 1

According to this site, back references \10 to \99 works on some languages, but not most.

Those that are reported to work are

• JGSoft
• Python
• PHP preg
• REAL basic