This issue came up because I was setting some values using the rand() function, then requesting them through a SOAP request where the were received as strings. A numeric comparison between two numers that were seemingly the same failed:

# these two variables are indentical when printed to STDOUT
$var1 = rand(1);
$var2 = $soapres->dataof('//path/to/elem/')->attr->{attr};

if ( $var1 == $var2 ) {
    print "all is well\n";
} else {
    print "got problems?\n";
}
[download]

The comparison invariably failed. However, when I did a string comparison, it succeeded.

# these two variables are indentical when printed to STDOUT
$var1 = rand(1);
$var2 = $soapres->dataof('//path/to/elem/')->attr->{attr};

if ( $var1 eq $var2 ) {
    print "all is well\n";
} else {
    print "got problems?\n";
}
[download]

I'm guessing that this has something to do with the internal representation of the value returned by rand(). I'm guessing that the value is stored internally with a greater precision, so the numeric comparison between that value and the "truncated" value fails.

Of course...this is just my theory.