Regular expression to match "="

In try to find a simple pattern p to match a single '=' but ignore '==' in a string

So I want

regexp('a = b', p)

to return 3

regexp('a == b', p)

to return [].

I try several things and they are all fail on '=='

>> regexp('a == b','=(?!=)')

ans =

     4

>> regexp('a == b','={1}')

ans =

     3     4

>> regexp('a == b','(?!==)=')

ans =

     4

Any suggestion for simple pattern?

Answer 1

[Walter Roberson]

regexp('a == b = d','(?<!=)=(?!=)')

This looks for = that are not preceded by = and not followed by =

[Bruno Luong]

Thanks