topic C fopen in Operating System - OpenVMS

C fopen

Bojan Nemec — Thu, 22 Jul 2004 05:04:52 GMT

Hi,

Can anyone explain me the behavior of the C fopen function?

There is what I mean:

A short C program:
#include
int main ()
{
FILE * f;
f = fopen ("A.TMP","w");
fclose (f);
return 1;
}

I run this program and if I do a directory/full I get:
.
.
Record format: Stream_LF, maximum 0 bytes, longest 32767 bytes
.
.

Then I type:
$ create a.tmp

The dir/full gives me:
.
.
Record format: Variable length, maximum 0 bytes, longest 0 bytes

Ok, another run of the program and dir/full gives me:
.
.
Record format: Variable length, maximum 0 bytes, longest 0 bytes

This means that the record format is obtained from the previous version of the file!

Regards
Bojan

Re: C fopen

Martin Vorlaender — Thu, 22 Jul 2004 05:13:31 GMT

>
This means that the record format is obtained from the previous version of the file!
<

This is documented behaviour, see
http://h71000.www7.hp.com/commercial/c/docs/5763p027.html#fopen_routine

cu,
Martin

Re: C fopen

Wim Van den Wyngaert — Thu, 22 Jul 2004 05:15:52 GMT

Others :

http://groups.google.com/groups?hl=nl&lr=&ie=UTF-8&threadm=3j6se9%24qp7%40gwdu19.gwdg.de&rnum=1&prev=/groups%3Fq%3D%2522previous%2520version%2522%2520fopen%2522%2520openvms%26num%3D100%26hl%3Dnl%26lr%3D%26ie%3DUTF-8%26sa%3DN%26tab%3Dwg

Re: C fopen

Bojan Nemec — Thu, 22 Jul 2004 05:34:26 GMT

Thank you,

I will modify my programs to force the attributes. Another #ifdef __VMS.

Bojan

Re: C fopen

Martin P.J. Zinser — Sun, 25 Jul 2004 16:46:22 GMT

Hello Bojan,

one way to minimize this particular ifdef

#ifdef VMS
#define FOPEN_OPT ...
#else
#define FOPEN_OPT ...
#endif

then use the FOPEN_OPT macro in the actual
fopen calls without any ifdefs. This also has the adavantage that if you decided you need to twiddle yet another knob the change is very well localized.

Greetings, Martin