Substituting everything from = to end of the line

Question

Let's say I have several lines like:

$repeat_on =  $_REQUEST['repeat_on'];    
$opt_days = $_REQUEST['opt_day'];  
$opt_days = explode(",", $opt_days);

... and so on.

Let's say I use visual mode to select all the lines: how can I replace everything from = to the end of the line so it looks like:

$repeat_on = NULL;    
$opt_days =  NULL;
$opt_days =  NULL;

Answer 1

With the block selected, use this substitute:

s/=.*$/= NULL;

The substitution regex changes each line by replacing anything between = and the end of the line, including the =, with = NULL;.

The first part of the command is the regex matching what is to be replaced: =.*$.

• The = is taken literally.
• The dot . means any character.
• So .* means: 0 or more of any character.
• This is terminated by $ for end of line, but this actually isn't necessary here: try it also without the $.

So the regex will match the region after the first = in each line, and replace that region with the replacement, which is = NULL;. We need to include the = in the replacement to add it back, since it's part of the match to be replaced.

When you have a block selected, and you hit : to enter a command, the command line will be automatically prefixed with a range for the visual selection that looks like this:

:'<,'>

Continue typing the command above, and your command-line will be:

:'<,'>s/=.*$/= NULL;

Which will apply the replacement to the selected visual block.

If you'll need to have multiple replacements on a single line, you'll need to add the g flag:

:'<,'>s/=.*$/= NULL;/g

Answer 2

Some alternatives:

Visual Block (fast)

On the first line/character do... Wl<C-v>jjCNULL;<Esc>bi<Space><Esc>

Macro (faster)

On the first line/character do... qqWllCNULL;<esc>+q2@q

:norm (fastest)

On the first line do... 3:no<S-tab> WllCNULL;<Enter>

Or if you've visually selected the lines leave the 3 off the beginning.