rvp@softserver.canberra.edu.au (Rey Paulo) (04/25/91)
Can anyone tell me if dynamically allocated storage for automatic variables
remains allocated even if the variables have already disappeared after the
invocation of the function. If it is, does this mean that "automatic" does
not have any meaning at all for dynamically allocated storage?
And one more, if I have an automatic variable in a function and I allocate
storage for that variable using "malloc", are the following ways of freeing
the storage the same? In both cases, assume the variable is (char *str).
1) free (str) - inside the function where str is declared.
2) free (sstr) - inside another function where sstr is declared but
made to point to str by a function call.
Thanx.
--
Rey V. Paulo | Internet: rvp@csc.canberra.edu.au
University of Canberra | I am not bound to please thee with my answer.
AUSTRALIA | -Shylock, in "The Merchant of Venice"
------------------------------+----------------------------------------------brister@decwrl.dec.com (James Brister) (04/26/91)
G'day, On 25 Apr 91 02:54:03 GMT, rvp@softserver.canberra.edu.au (Rey Paulo) said: > Can anyone tell me if dynamically allocated storage for automatic variables > remains allocated even if the variables have already disappeared after the > invocation of the function. You're not clear on what you mean here. Given the following two lines in a function: char *str ; str = malloc (x) ; are you referring to the space taken up by str? Or that space taken up by *str? (i.e. the space returned by the malloc())? The space taken up by str will generally be on a stack, and will be receovered by the function returning. The malloced space will not be reclaimed automatically and this will give you a memory leak in your program, unless you keep track of the space through another pointer other than str. > If it is, does this mean that "automatic" does not have any meaning at > all for dynamically allocated storage? When you say dynamcially you mean malloc'ed, right? Them this is true. The "auto" storage class modifier isn't very useful (IMHO), because variables inside a function are automatic by default. > And one more, if I have an automatic variable in a function and I allocate > storage for that variable using "malloc", are the following ways of freeing > the storage the same? In both cases, assume the variable is (char *str). > 1) free (str) - inside the function where str is declared. > 2) free (sstr) - inside another function where sstr is declared but > made to point to str by a function call. Yes > University of Canberra | I am not bound to please thee with my answer. > AUSTRALIA | -Shylock, in "The Merchant of Venice" Nor am I! ;-) James -- James Brister brister@decwrl.dec.com DEC WSL., Palo Alto, CA {uunet,pacbell,pyramid}!decwrl!brister "Old mathematicians never die; they just lose some of their functions."