[Yutaka Emura]

You can use Replacement Expressions using JavaScript:

For example,

replacing

.*

with

\J "\0".length;

with the Regular Expressions option will replace the strings with their length.

Please watch:

https://youtu.be/xWUX37VHrTM

for more information about Replacement Expressions using JavaScript.

Alternatively, select the second or righter column, and replacing with

\J cell( -1 ).length;

will count the cell on the left.

Also see: http://www.emeditor.org/en/howto_search_replacement_expression_syntax.html