Regex to filter words containing english alphabets

[wysota]

The fastest approach I can think of is to use something similar to QStringRef where you will not copy the data from the original string in every iteration but instead mark positions and lengths of every valid token and at the end extract those tokens from the string in one go, possibly with merging the marks so that you can extract as large areas as possible. Then you avoid the split, avoid copying data and other expensive operations. And you will omit the effect of your current implementation that doesn't preserve whitespaces.

[dipeshtech]

I have to try it out...!! Not getting it at present, but will try it for sure.

It's already dawn here, will try after some rest.