malloc_usable_size(3) Library Functions Manual malloc_usable_size(3) malloc_usable_size - (libc -lc) #include size_t malloc_usable_size(void *_Nullable ptr); malloc(3) . malloc_usable_size() ptr. ptr (NULL) 0. attributes(7). +------------+------------------------------------+--------------------+ || | | +------------+------------------------------------+--------------------+ |malloc_usable_size()| | MT-Safe | | | | | +------------+------------------------------------+--------------------+ GNU. malloc_usable_size() . realloc(3) . . malloc(3) 3 . . : . 6.18 8 2026 malloc_usable_size(3)