Notepad++ v6.3.2 backreference regex replace not working

Question

I have seen the instructions on using $1 in order to backreference the replace, but it is not working for me. Example:

I search for

<header

to replace with

$1 class="bold"

and instead of <header class="bold" I get $1 class="bold"

Am I missing something?

Answer 1

You must understand that $n refer to the capturing group number n. Since you don't have capturing groups in your search pattern, the group number 1 doesn't exist:

You must use capturing parenthesis to define a group, example:

search:  (<header)
replace: $1 class="bold"

Another example:

search:  (<)(header)
replace: $1$2 class="bold"

Notice: $0 refers to the whole match (without define any capturing group). Then you can write:

search:  <header
replace: $0 class="bold"