struct iovec is defined in <uio.h> by the following way:

/* Structure for scatter/gather I/O.  */
struct iovec
    void *iov_base; /* Pointer to data.  */
    size_t iov_len; /* Length of data.  */

Now I do ugly casting from const void* to void*:

int send_frame_once( int fd, const struct iovec* iov, size_t iovlen );

int send_frame( int fd, const void* buffer, size_t len )
    struct iovec iov;
    iov.iov_base = (void*)buffer;       /* const iov cast */
    iov.iov_len  = len;
    return send_frame_once( fd, &iov, 1 );

Is that necessary kludge? Or should I remove const keyword from declaration of send_frame function. Like this:

int send_frame( int fd, void* buffer, size_t len )

1 Answer 1


I think you should keep it. const is not only meant for the compiler, but also for anybody reading your code. Even with the void* cast, you're still saying to readers "Trust me, I'm not touching your buffer!" and this is a valuable information that should not be discarded.

  • 2
    \$\begingroup\$ assuming send_frame does not alter the content of buffer in any way. \$\endgroup\$ Feb 29, 2012 at 14:34
  • \$\begingroup\$ Indeed, this is what I am assuming here. \$\endgroup\$ Feb 29, 2012 at 14:35
  • 1
    \$\begingroup\$ Yep, buffer is not modified. \$\endgroup\$
    – SKi
    Mar 1, 2012 at 8:06

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