Question

I would like to create a regex which will allow me to add spaces around assignment operators in C++ code (as I prefer this style), e.g. so that

x=something

becomes

x = something

but

if(y==x)

does not become

if(y = = x)

and so on including !=,<=,>=

I am relatively new to regular expressions and have tried the following:

(?<![\s=])(=)(?!=)

I thought this would be a good starter, but this does not seem to match. Could someone explain what I have not understood about regex here?

Edit

Example using regex which does not match in Code::Blocks IDE

Answer 1

Try something like this: (?<![<>=!])\s*=\s*(?!=) replaced with =.

OR

([^<>=!])\s*=\s*([^=]) replaced with \1 = \2

Both lookaround assertions are needed since the pattern is not anchored.

Your own regex was, in reality, just missing <> in the character class. I have improved on it a tiny bit, look at the demo.

Demo+explanation for first regex: http://regex101.com/r/kU1hP2
Demo+explanation for second regex: http://regex101.com/r/lK1oQ3

Note: \s matches whitespace!