Using vim to replace string functions with their multi-byte equivalent

The PHP INI option mbstring.func_overload override certain string functions (like strpos, substr, etc.) with multi-byte aware implementations. This makes it super easy to migrate a legacy code base to UTF-8, but immediately restricts interaction with vendor products (Symfony, Net_DNS2, etc.).

The proper integration is to manually replace string functions with their multi-byte equivalent. In one legacy code base I'm improving, there are on the order of 10k instances of these functions. I want to change and verify each replacement, but I don't want to type much. Time for some vim-fu:

:argdo %s/strpos/mb_strpos/gc | wn

This performs a confirmed find and replace, writes the change to disk, then moves on to the next file.