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Re: malloc

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In <4dbcfa24$0$8384$bbae4d71@news.suddenlink.net> "Bill Cunningham" <nospam@nspam.invalid> writes:


>     Let me see if I can make this easier to understand.

> fread(p,sizeof(int),20,fp);

> Ok nothing will go above 20 size_t's but if only 15 size_t's are filled I 
> want to return 5 to memory. Is there a way to do that?

Allocate a suitably large buffer with malloc().
Call fread() to put stuff in the buffer.
If the buffer ends up being too large, resize it with realloc().

I noticed a problem with your original code:

> char p[20];
> t = fread(p, sizeof(int), 20, fp);

p is declared as an array of 20 characters, however you're trying to stuff
20 ints into it, which is too much.  If you know you will put ints into p,
declare it that way.

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon@panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"

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malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-01 01:01 -0400
  Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-01 01:03 -0400
  Re: malloc luser- -droog <mijoryx@yahoo.com> - 2011-04-30 22:31 -0700
    Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-01 02:15 -0400
    Re: malloc "BartC" <bc@freeuk.com> - 2011-05-01 13:52 +0100
      Re: malloc luser- -droog <mijoryx@yahoo.com> - 2011-05-02 00:05 -0700
        Re: malloc crisgoogle <crisd@telus.net> - 2011-05-02 17:43 -0700
  Re: malloc Ian Collins <ian-news@hotmail.com> - 2011-05-01 17:35 +1200
  Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-01 02:14 -0400
    Re: malloc Mickey Mouse <fake@email.com> - 2011-05-01 00:18 -0700
      Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-01 04:07 -0400
        Re: malloc Barry Schwarz <schwarzb@dqel.com> - 2011-05-01 10:31 -0700
          Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-02 16:55 -0400
          Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-02 23:51 -0400
      Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-02 16:58 -0400
        Re: malloc Mickey Mouse <fake@email.com> - 2011-05-02 14:34 -0700
          Re: malloc Ian Collins <ian-news@hotmail.com> - 2011-05-03 09:55 +1200
            Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-03 10:20 -0400
              Re: malloc Angel <angel+news@spamcop.net> - 2011-05-03 14:55 +0000
                Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-03 15:34 -0400
                Re: malloc Angel <angel+news@spamcop.net> - 2011-05-03 20:56 +0000
            Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-03 11:29 -0400
          Re: malloc Seebs <usenet-nospam@seebs.net> - 2011-05-02 22:18 +0000
          Re: malloc "Default User" <defaultuserbr@yahoo.com> - 2011-05-04 12:20 -0500
            Re: malloc Keith Thompson <kst-u@mib.org> - 2011-05-04 10:52 -0700
              Re: malloc Joe Wright <joewwright@comcast.net> - 2011-05-04 14:57 -0400
              Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-04 18:53 -0400
                Re: malloc Angel <angel+news@spamcop.net> - 2011-05-05 08:12 +0000
    Re: malloc John Gordon <gordon@panix.com> - 2011-05-02 15:31 +0000
  Re: malloc "osmium" <r124c4u102@comcast.net> - 2011-05-01 09:56 -0500
    Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-01 18:20 -0400
    Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-02 21:38 -0400
      Re: malloc "osmium" <r124c4u102@comcast.net> - 2011-05-03 09:02 -0500
        Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-03 15:21 -0400
          Re: malloc "osmium" <r124c4u102@comcast.net> - 2011-05-03 14:35 -0500
            Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-03 18:43 -0400
  Re: malloc Tim Rentsch <txr@alumni.caltech.edu> - 2011-05-01 12:51 -0700
    Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-02 23:49 -0400
      Re: malloc Ian Collins <ian-news@hotmail.com> - 2011-05-03 13:35 +1200
        Re: malloc "Bill Cunningham" <nospam@nspam.invalid> - 2011-05-03 11:27 -0400
          Re: malloc Ian Collins <ian-news@hotmail.com> - 2011-05-04 07:54 +1200
          Re: malloc Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-03 21:50 +0100

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