How to replace . character within code with regex?

Question

I already read outer StackOverflow posts and tried the online regex websites.

I want to replace a dot with an underscore:

aab.ccc --> aab_ccc

but in the Matlab code are calculations:

cost11 =aab.ccc*(v1.^3.*t11  + 1.5*v1.*a1.*t11.^2+ a1.^3.*t11./4/4) + aab.ccc.*t11;

The dots .^ .* ./ should not be replaced. My regex looks like this: \.(?!(\^|\*|\/)$), but it still selects all dots. I also use this regex tool: https://regex101.com/r/rMbYHz/306

What is missing in the regex?

Do you mean like \.(?![\^*\/\d]) regex101.com/r/qvzkA6/1 also excluding the digits? — The fourth bird
– The fourth bird, Commented Apr 23, 2020 at 9:25

The fourth bird · Accepted Answer · 2020-04-23 09:37:06Z

1

For the example data, you could use:

\.(?![*\/\d^])

In parts:

\. Match a dot
(?! Negative lookahead
- [*\/\d^] Match either * / a digit or ^
) Close lookahead.

Regex demo

Note that for the pattern (\^|\*|\/)$ you can shorten the alternation using the | to a character class without the pipe. Using $ asserts the end of the string, which can be omitted from the pattern.

edited Apr 23, 2020 at 9:37

answered Apr 23, 2020 at 9:31

The fourth bird

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Comments

Davey van Tilburg · Accepted Answer · 2020-04-23 09:27:53Z

1

Remove the $

\.(?![\^|\*|\/])

https://regex101.com/r/Qwbcoc/1

answered Apr 23, 2020 at 9:27

Davey van Tilburg

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2 Comments

j35t3r Over a year ago

but now it also replaces the dot at the digits. I think that better is to add use this one: \.(?!(\^|*|\/|[0-9]))

Davey van Tilburg Over a year ago

Well you didn't say that in your question @j35t3r haha, but it seems the fourth bird has thought of that too! Use his answer :)

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