Description:
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PHP seems to incorrectly convert strings beginning with "inf" to INF (infinity).  This includes converting strings such as "info" and "inflammable".  Surprisingly, the strings "inf" and "infinity" do *not* convert to infinity but correctly become zeros.  A script that illustrates the problem is given below:

This is very annoying because one cannot simply do a test for a positive number with code such as

  if ($x>0) { echo "$x is positive"; }

because if $x is any string beginning with "inf" (but not "inf" or "infinity") it is treated as a positive number.  

Pm

Reproduce code:
---------------
Here's a script that illustrates the problem:

<?php
  header("Content-type: text/plain");
  $a = "into";
  $b = "info";
  $c = "inf";
  $d = "infinity";
  $e = "infin";
  $f = "inflammable";

  echo "a: $a == ",$a+0,"\n";   # outputs 0 (correct)
  echo "b: $b == ",$b+0,"\n";   # outputs INF, incorrect!
  echo "c: $c == ",$c+0,"\n";   # outputs 0 (?!)
  echo "d: $d == ",$d+0,"\n";   # outputs 0 (?!)
  echo "e: $e == ",$e+0,"\n";   # outputs INF, incorrect!
  echo "f: $f == ",$f+0,"\n";   # outputs INF, incorrect!
?>


Expected result:
----------------
a: into == 0
b: info == 0
c: inf == 0
d: infinity == 0
e: infin == 0
f: inflammable == 0

Actual result:
--------------
a: into == 0
b: info == INF
c: inf == 0
d: infinity == 0
e: infin == INF
f: inflammable == INF