How does strstr() work?

[Yann E. MORIN]

Jody, All,

On 2015-01-04 10:04 -0500, Jody Bruchon spake thusly:
> I was looking at the code for strstr(s1, s2) and I do not understand how it
> does what it's supposed to do. The only exit points return NULL or the
> original pointer to s1. How does strstr() return the pointer to the
> substring it's supposed to be looking for?

You're missing line 35:

   23     do {
   24         if (!*p) {
   25             return (Wchar *) s1;;
   26         }
   27         if (*p == *s) {
   28             ++p;
   29             ++s;
   30         } else {
   31             p = s2;
   32             if (!*s) {
   33                 return NULL;
   34             }
   35             s = ++s1;            <-- here, we modify s1.
   36         }
   37     } while (1);

Regards,
Yann E. MORIN.

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