On Fri, 25 Dec 1998, Nuno Carvalho wrote:
> Hi,
>
> Is there some way to open a file with fopen() on mode "r+b" but if the
> file doesn't exist it create a new one automatically !?
>
> I only can do it with "a+b" but I don't want the append command !
If you don't want to truncate an existing file use something
along the lines of:
/* ANSI C */
char *MYFILE="./somefile";
FILE *foo;
if( NULL == (foo=fopen(MYFILE, "r+")) )
{
if( NULL == (foo=fopen(MYFILE, "w+")) )
{
fprintf(stderr, "Couldn't open file:%s\n",MYFILE);
return -1;
}
}
The stream is at the beginning of the file in both cases. If
you want to truncate a file if it exists, or create it if it
does not exist then use fopen(MYFILE, "w+"). It is all covered
in the fopen man page.
I suspect that you don't know the ANSI C functions very
well, as your question is basic ANSI C. If this is true
then you should start reading up on:
int fseek( FILE *stream, long offset, int whence);
long ftell( FILE *stream);
void rewind( FILE *stream);
int fgetpos( FILE *stream, fpos_t *pos);
int fsetpos( FILE *stream, fpos_t *pos);
and you will be enlightened.
