Fast strcmp() wanted.

[Kent Paul Dolan]

falk at peregrine.Sun.COM (Ed Falk) writes:
> sartin at hplabs.hp.com (Rob Sartin) writes:
>> cedman at lynx.ps.uci.edu (Carl Edman) writes:
>>>string structure (or better class, long live C++ ! :-) which calculates
>>>a 32-bit CRC for each string the first time and stores it somewhere.
>>>Then only 1 (inlined) longword-compare will do the stringcomparisons
>>>for you.
>>
>>Afraid not.  It'll give you an estimate of whether the strings match
>>(correctly identifying those that don't).  You will need to then
>>actually compare the strings if they are the same.  This method will
>>also be unable to reproduce strcmp's behavior (strcmp returns a signed
>>result indicated the <, =, > by being negative, zero, positive), it will
>>only return a boolean (match, no match).
>
>Also, these two strings
>
>	"ab\0x"
>	"ab\0y"
>
>(where x and y are any garbage that happens to be in memory after the
>terminating '\0') will be evaluated as unequal.

For an exclusive or or other 16 bit at a time checksum, perhaps, but a
properly designed CRC (which is a bitwise operation on the string) would
stop at the end of the byte before the null byte.

Kent, the man from xanth.
<xanthian at Zorch.SF-Bay.ORG> <xanthian at well.sf.ca.us>