On 09/20/2017 10:25 PM, Stefan Beller wrote:
> On Mon, Sep 18, 2017 at 11:22 PM, Michael Haggerty <mhag...@alum.mit.edu>
> wrote:
>> [...]
>> +/* Return -1, 0, 1 if refname is before, inside, or after the prefix. */
>> +static int compare_prefix(const char *refname, const char *prefix)
>> +{
>> + while (*prefix) {
>> + if (*refname != *prefix)
>> + return ((unsigned char)*refname < (unsigned
>> char)*prefix) ? -1 : +1;
>
> This looks interesting.
>
> We get a signed char* , cast it to unsigned char* and then
> compare byte by byte.
Not quite. We get a `char *` of unknown signedness (it's
implementation-dependent), dereference it into a `char`, then cast that
value to `unsigned char`. What you described would be
*(const unsigned char *)refname < *(const unsigned char *)prefix
But I assume that these two variants would result in identical assembly
code.
> [...]
Michael
