The nng_strfree() function deallocates the string str. This is equivalent to using nng_free() with the
length of str plus one (for the NUL terminating byte) as the size.
Important
This should only be used with strings that were allocated by nng_strdup() or nng_alloc(). In all
cases, the allocation size of the string must be the same as strlen(str) + 1.Important
Consequently, if the a string created with nng_strdup() is modified to be shorter, then it is
incorrect to call this function. (The nng_free() function can be used instead in that case, using the
length of the original string plus one for the size.)