Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

When performing a mathematical calculation between a number and a string in PHP, PHP will attempt to convert the string to an integer. Since PHP supports things such as INF certain strings, such as 'inf more data' will be converted to INF.

Ok, double-checked the documentation: this behavior of 'inf...' strings seems absolutely undocumented.

Auto-convertion of any string that begins by 'inf' in infinite seems to me inadequate. Considering that this 'functionality' has not been documented, would be desirable to create a new predefined constant INF or a new data type INF or a new reserved word INF to treat infinite numbers, in the same form in which NULL, TRUE or FALSE correspond to 
predefined values. Consider that when we locked up 'NULL', 'TRUE' or 'FALSE' in a string, they are not evaluated like the corresponding constants. The same behavior would be desirable with a (new) predefined constant INF.

And at least an error exists now in the form in which the strings that begin by 'inf' are treated. The strings of more than 3 characters ('information', 'infant' ...) are evaluated as INF in the comparisons with numbers, but the string 'inf', with single three characters, does not. Try this:

<?
echo (double)'information', '<br>';
echo (double)'inf'        , '<br>';

echo 'information' > 1 ? 1 : 0, '<br>';
echo 'inf'         > 1 ? 1 : 0, '<br>';
?>

Result:

INF
INF
1
0

Saludos
?ngel

Re-open: at least with single three characters 'inf', this is a bug and not a 'functionality'.

We're already discussing this - so reopening was valid.

verified with PHP 4.3.1-dev..

This bug is the result of differing implementations of strtod() in the various libc libraries. For example glibc considers (double) "info" to be equivalent to INF while in Win32 the same operation will return 0.