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Content-Type: multipart/alternative; boundary=001a113aac1ec200fe050439c61a
Subject: [Caml-list] Str, regular expressions, longest match

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Dear All,

I am trying to use the Str module to match regular expressions. I want to
return the longest match.

let txt = "ab"
let reg = "a\\|ab"
let _ =
  let b = Str.string_match (Str.regexp reg) txt 0 in
  Str.matched_string txt

After the last line, the string "a" is apparently matched. But I hope that
the result should be "ab". If I reverse the order of the alternatives in
the regular expression, the string "ab" is matched. I don't want the order
of the alternatives to matter. What am I doing wrong? What can I do to
match the longest substring?

Thanks

Tom

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Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">Dear All,<div><br></div><div>I am trying to use the Str mo=
dule to match regular expressions. I want to return the longest match.</div=
><div><br></div><div><div><div>let txt =3D &quot;ab&quot;</div><div>let reg=
 =3D &quot;a\\|ab&quot;</div><div>let _ =3D=C2=A0</div><div>=C2=A0 let b =
=3D Str.string_match (Str.regexp reg) txt 0 in</div><div>=C2=A0 Str.matched=
_string txt</div></div></div><div><br></div><div>After the last line, the s=
tring &quot;a&quot; is apparently matched. But I hope that the result shoul=
d be &quot;ab&quot;. If I reverse the order of the alternatives in the regu=
lar expression, the string &quot;ab&quot; is matched. I don&#39;t want the =
order of the alternatives to matter. What am I doing wrong? What can I do t=
o match the longest substring?</div><div><br></div><div>Thanks</div><div><b=
r></div><div>Tom</div></div>

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