inconsistency in converting string to integer, when string is hex, prefixed with '0x'

Using PHP 5.3.5. Not sure how this works on other versions.

I'm confused about using strings that hold numbers, e.g., '0x4B0' or '1.2e3'. The way how PHP works with such strings seems inconsistent to me. Is it only me? Or is it a bug? Or undocumented feature? Or am I just missing some magic sentence in docs?

<?php

echo $str = '0x4B0', PHP_EOL;
echo "is_numeric() -> ", var_dump(is_numeric($str)); // bool(true)
echo "*1           -> ", var_dump($str * 1);         // int(1200)
echo "(int)        -> ", var_dump((int)$str);        // int(0)
echo "(float)      -> ", var_dump((float)$str);      // float(0)
echo PHP_EOL;

echo $str = '1.2e3', PHP_EOL;
echo "is_numeric() -> ", var_dump(is_numeric($str)); // bool(true)
echo "*1           -> ", var_dump($str * 1);         // float(1200)
echo "(int)        -> ", var_dump((int)$str);        // int(1)
echo "(float)      -> ", var_dump((float)$str);      // float(1200)
echo PHP_EOL;

In both cases, is_numeric() returns true. Also, in both cases, $str * 1 parses string and returns valid number (integer in one case, float in another case).

Casting with (int)$str and (float)$str gives unexpected results.

• (int)$str in any case is able to parse only digits, with optional "+" or "-" in front of them.
• (float)$str is more advanced and can parse something like ^[+-]?\d*(\.\d*)?(e[+-]?\d*)?, i.e., optional "+" or "-", followed by optional digits, followed by optional decimal point with optional digits, followed by optional exponent which consists of "e" with optional "+" or "-" followed by optional digits. Fails on hex data though.

Related docs:

• is_numeric() - states that "Hexadecimal notation (0xFF) is allowed too but only without sign, decimal and exponential part". If function, meant to test if a string holds numeric data, returns true, I expect PHP to be able to convert such string to a number. This seems to work with $str * 1, but not with casting. Why?
• Converting to integer - states that "in most cases the cast is not needed, since a value will be automatically converted if an operator, function or control structure requires an integer argument". After such statement, I expect both $s * 10 and (int)$s * 10 expressions to work the same way and to return the same result. Though, as shown in example, those expressions are evaluated differently.
• String conversion to numbers - states that "Valid numeric data is an optional sign, followed by one or more digits (optionally containing a decimal point), followed by an optional exponent". "Exponent" is "e" or "E", followed by digits, e.g., 1.2e3 is valid numeric data. Sign ("+" or "-") is not mentioned. It does not mention hexidecimal values. This conflicts with definition of "numeric data" used in is_numeric(). Then, there is suggestion "For more information on this conversion, see the Unix manual page for strtod(3)", and man strtod describes additional numeric values (including HEX notation). So, after reading this, is hexidecimal data supposed to be valid or invalid numeric data?

So...

• Is there (or, rather, should there be) any relation between is_numeric() and the way how PHP treats strings when they are used as numbers?
• Why do (int)$s, (float)$s and $s * 1 work differently, i.e,. give completely different results, when $s is 0x4B0 or 1.2e3?
• Is there any way to convert a string to a number and keep its value, if it is written as 0x4B0 or as 1.2e3? floatval() does not work with HEX at all, intval() needs $base to be set to 16 to work with HEX, typecasting with (int)$str and (float)$str sometimes works, sometimes does not work, so these are not valid options. I'm also not considering $n *= 1;, as it looks more like data manipulation rather than converting. Self-written functions also are not considered in this case, as I'm looking for native solution.