How to put space before and after operators for enhanced readability?

Question

I want -

• variable++; then variable ++;
• variable1 + variable2 nothing to do
• variable1 +variable2 then variable1 + variable2
• variable1+ variable2 then variable1 + variable2
• variable1+variable2 then variable1 + variable2

similarly for -,*,/,>=,<=,!=,==.
And if -

• variable1 = variable2 then nothing to do
• variable1 =variable2 then variable1 = variable2
• variable1= variable2 then variable1 = variable2
• variable1=variable2 then variable1 = variable2

I try the search regex as [a-zA-Z]+([-+/*=]|>=|<=|!=|==) although it is not correct fully.

Answer 1

One way to do this would be this:

First change the infix operators:

:%s/\v(\w) ?(\+|-|\*|\/|\>\=|\<\=|!\=|\=|\=\=) ?(\w|-)/\1 \2 \3/g

N.B. This also handles the int x=-b case mentioned in the comments.

Then the postfix ++:

:%s/\v(\w)\+\+/\1 ++/g

Broken down, that first regular expression is:

• \v: Turn on "very magic" matching.
• (\w) ?: Find a "word character" optionally followed by a space, capturing the word character into a group.
• (\+|-|\*|\/|\>\=|\<\=|!\=|\=|\=\=): Find any of +, -, *, /, >=, <=, !=, =, or ==, capturing it into a second group.
• _?(\w|-): Find another optional space (represented here as an underscore so you can see it!) followed by another word character (or minus symbol), captured into the third group.

We then replace the entire match with the contents of the three groups, separated by spaces:

\1 \2 \3

For more info, see :help regexp, and specifically:

• :help \magic
• :help \w
• :help \?
• :help \|
• :help \1