Use asManyOfPattern to match as many individual letters as possible between two instances of "b".

Create txt as a string. Create a pattern, pat, that matches as many of the letters "a" or "b" as possible between two instances of the character "b".

txt = "bb bab babab babaaabab";
pat = "b" + asManyOfPattern("a"|"b") + "b";

Use replace to replace text matched by pat with the character "*".

replace(txt,pat,"*")

ans = 
"* * * *"

Use asManyOfPattern to match as many individual letters as possible between two instances of "b", but require at least three letters.

Create txt as a string. Create a pattern, pat, that matches as many of the letters "a" or "b" as possible between two instances of the character "b" but specify that there must be a minimum of three matched letters.

txt = "bb bab babab babaaabab";
pat = "b" + asManyOfPattern("a"|"b",3) + "b";

Use replace to replace text matched by pat with the character "*".

replace(txt,pat,"*")

ans = 
"bb bab * *"

Use asManyOfPattern to match as many individual letters as possible between two instances of "b", but require at least three and no more than four letters.

Create txt as a string. Create a pattern, pat, that matches as many of the letters "a" or "b" as possible between two instances of the character "b", but specify that there must be a minimum of three and a maximum of four matched letters.

txt = "bb bab babab babaaabab";
pat = "b" + asManyOfPattern("a"|"b",3,4) + "b";

Use replace to replace text matched by pat with the character "*".

replace(txt,pat,"*")

ans = 
"bb bab * ba*ab"