Replace the string matching a specific regular expression with a length in Vim

Question

In Vim, how to replace a string corresponding to a certain regular expression with its length, for example:

Regexp = "\ w *"

hello → 5
"bye" → "3"

Can this be done with: s or do I need to write some script?

Best wishes

Answer 1

Replace 'hello' with a regex expression expression, and this should work in VIM:

:s/hello/\=strlen(submatch(0))/