in reply to How to remove all repeating characters in a string in place

What have you tried so far?

There are many ways to do this, most of which are documented in any tutorial about regular expressions. Try Regular Expressions Tutorial, the Basics (for BEGINNERS). After a few paragraphs, there is the section entitled Substitution Operators, and that should tell you what you need to know.

Update: the following section on character classes will also be useful, I think.

But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us. Romans 5:8 (NASB)
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