Question

Quoting style

The most obvious solution is to only replace quotes with a nonword character on at least one side. Something like /\W'|'\W/ . But you also have to take the start and end of the line into account.

In addition, you must ensure that the replacement also includes the characters that were matched by the \W pattern so that those are not dropped. This can be done by wrapping them in parentheses and including their groups in the replacement string ( $1 , $2 ). Groups that are not matched will be replaced by nothing.

Numbers again

First, do not forget the backslash in front of the dot.

Matching the optional sign in front of the number, as well as in front of the exponent, can be done with [+\-]? or (\+|-|) (plus, minus, or nothing).

The more complicated part of the exercise is the problem of matching both "5." and ".5" without also matching "." . For this, a good solution is to use the | operator to separate the two cases—either one or more digits optionally followed by a dot and zero or more digits or a dot followed by one or more digits.

Finally, to make the e case-insensitive, either add an i option to the regular expression or use [eE] .

This is a book about getting computers to do what you want them to do. Computers are about as common as screwdrivers today, but they contain a lot more hidden complexity and thus are harder to operate and understand. To many, they remain alien, slightly threatening things.