Strip leading whitespace, extract an optional +/- sign,
and an optional radix prefix. If the radix value matches
an optional prefix, or the radix is zero, the prefix will
be consumed and assigned. Where the radix is non zero and
does not match an explicit prefix, the latter will remain
unconsumed. Otherwise, radix will default to 10.
Strip leading whitespace, extract an optional +/- sign, and an optional radix prefix. If the radix value matches an optional prefix, or the radix is zero, the prefix will be consumed and assigned. Where the radix is non zero and does not match an explicit prefix, the latter will remain unconsumed. Otherwise, radix will default to 10.
Returns the number of characters consumed.