memcached_get (memcached_st *ptr,
const char *key, size_t key_length,
size_t *value_length,
uint32_t *flags,
memcached_return_t *error);
Why need to pass the params "size_t key_length" and "size_t *value_length" here ? I think the value can be fetched by key directly.
who can help to tell me the reason, thanks.
The key parameter is a pointer to an identifier for the information you want to get from memcache. The key_length tells the memcached_get() function how long your identifier data is.
If the libmemcache API assumed that the data pointed to by the key parameter was a NULL-terminated string of characters, then we wouldn't need to also pass in the key_length parameter. But by not making that assumption the API allows us to use data other than NULL-terminated char strings as keys (for example, UTF-16 strings, or binary numbers).