Can we use the relational operator in gsub?

Question

I need to replace the . character with . \n in the following string format. But, the constraint is, don't replace the . character with .\n in following pattern string only.

"test was done and was negative. Urine dipstick: ph = 6\\n \\342\\200\\242 spec. Grav.  = 1.015"

I need the following output, like

"test was done and was negative. \n Urine dipstick: ph = 6\\n \\342\\200\\242 spec. Grav.  = 1.015"

The constraint is => "spec. Grav. = 1.015".

Answer 1

str.gsub(/\.(?! (Grav| =))/, ".\n")

should do the job.

Brief explanation

• \. matches any .
• (?!) denotes a negative look-ahead. That means that it won't match anything found in these brackets.
• (Grav| =) hence a dot followed by either Grav or = won't be matched.

Answer 2

str = "test was done and was negative. Urine dipstick: ph = 6\\n \\342\\200\\242 spec. Grav.  = 1.015"

puts str.sub('. ', ".\n") 

#=> test was done and was negative.
#=> Urine dipstick: ph = 6\n \342\200\242 spec. Grav.  = 1.015

String.sub only substitutes the first match.

Answer 3

You want this?

str.gsub(/\.(?!\n)/, "\.\n")