Can the performance of this sequential search algorithm (taken from The Practice of Programming) be improved using any of C's native utilities, e.g. if I set the i variable to be a register variable ?
int lookup(char *word, char*array[])
{
int i
for (i = 0; array[i] != NULL; i++)
if (strcmp(word, array[i]) == 0)
return i;
return -1;
}
To optimize that code the best bet would be to rewrite the strcmp routine since you are only checking for equality and don't need to evaluate the entire word.
Other than that you can't do much else. You can't sort as it appears you are looking for text within a larger text. Binary search won't work either since the text is unlikely to be sorted.
My 2p (C-psuedocode):
wrd_end = wrd_ptr + wrd_len;
arr_end = arr_ptr - wrd_len;
while (arr_ptr < arr_end)
{
wrd_beg = wrd_ptr; arr_beg = arr_ptr;
while (wrd_ptr == arr_ptr)
{
wrd_ptr++; arr_ptr++;
if (wrd_ptr == wrd_en)
return wrd_beg;
}
wrd_ptr++;
}