Why is sprintf ifdef-ed out of <stdio.h>?

[Bob Weissman]

/usr/include/stdio.h has the declaration of sprintf() ifdef-ed out:

    /*      @(#)stdio.h 1.12 88/02/07 SMI; from UCB 1.4 06/30/83    */
    ...
    #ifdef vax
    char    *sprintf();             /* too painful to do right */
    #endif

Why is this?  It implies programs which use it have to declare it
themselves.

And what is so painful about the ifdef-ed out declaration, anyway?

Bob Weissman
Domainish: bob at omni.com
UUCPish:   ...!{amdahl,apple,pyramid,sgi,tekbspa,uunet}!koosh!bob