Difficulty with query-replace-regexp

Question

I'm having trouble getting query-regex-replace to do what I want. I've read the docs several times and still can't figure it out. Here are a few examples of things I can't figure out how to do with query-regex-replace:

1. Replace a bunch of whitespace on one line followed by "*" with just "*" (get rid of the whitespace.

EDIT - I got this to work with [[:space:]]+\* RET * RET

2. Replace two forward slashes followed by non white space with two forward slashes and white space (insert a space before the first non white space character).

EDIT - I also got this to work with //\([^[:space:]]+\) RET // \1

3. Get rid of blank lines (optionally of course because this is a query replace).

EDIT - I still cannot get this to work. Among other things, I tried these:

)[[:space:]]+{ RET ) { RET

and

)\s-+{ RET ) { RET

Thanks for any help.

Answer 1

To replace space and/or tab sequence followed by an asterisk to just an asterisk:

[ LiteralTabHere]+\*
*

That LiteralTabHere should be a literal tab char. Enter it by pressing C-q C-i.

You need the backslash before asterisk. Because the asterisk is a meta char, it means 0 or more items.

To insert a space before the first non-white-space character after 2 slashes:

//\([[:graph:]]+\)
// \1

To remove blank lines

\n\n\n+
\n\n

Each \n must be a literal return. To insert literal return, press C-q C-j.