tf_write_record(), sf_write_record()

Purpose

Writes a DP4 record to a file

Old names

#define _vwrite tf_write_record
#define _awrite sf_write_record

Syntax (CCOWN)

void tf_write_record(file_handle, short *datarec)
void sf_write_record(int file_handle, short *datarec)

Syntax (DP4DBAPI)

BOOLEAN dp4_sf_write_record(FCONN * fconn,const short * datarec)

Parameters

int file_handle,

File handle of file

 

FCONN * fconn

File handle of file

 

short* datarec

Pointer to the data to write to the file. The first two bytes must specify the length of the record.

Description

The tf_write_record() and sf_write_record() functions write a DP4 record to the current position in a file. You obtain the file handle with a successful call to tf_open() or sf_open().

The sf_write_record() function calls the file handling support in the database manager, and the tf_write_record() function calls the file handling support in the terminal manager. You must not mix up the server file functions with terminal file functions.

A DP4 record is a record corresponding to a structure of the form below:

struct MY_RECORD
{
   short l; /* and normally but not necessary */
   short typenr;
   short generation;
   short flags;
   long timestamp;
   /* other fields */
   ...
}

The L field is used to determine the number of bytes to write to the file. The file pointer is automatically incremented.

See also

tf_read_record(), tf_open()

Example

 
/*
 C Functions Reference Manual
 ----------------------------
 Filename: TF_WRITE.C
 Example: tf_write_record
 Purpose: Program fetches all the customer records
          and  writes them to the file CUSTOMER.EXT.
*/

/*
#db salesord
#c
#tables customer;
#end
*/

#include "dp4.h"
#include "tf_write.h"
  /* generate this file by running LIBMAKE */
void process()
{
   int fd;
   int srch = FIRST;
   map_draw(1,RETAIN); /* header map */
   /* open CUSTOMER.EXT for read/write, as new, and
      write in sequence */
   fd = tf_open("CUSTOMER.EXT",VF_RW|VF_NEW|VF_SEQ);
   if (fd > 0)
   {
      map_draw(2,RETAIN); /* progress map */
      /* fetch, display and post the records to
         CUSTOMER.EXT */
      while (rec_fetch_main(srch,&customer.l))
      {
         srch = NEXT;
         show_c(2,1,customer.name);
         show_n(2,2,customer.customer_number);
         show_c(2,3,customer.address[0]);
         trm_refresh();
         /* make count visible */
         tf_write_record(fd,&customer.l);
      }
   }
   else
     askf_special(3,1,0);
     /* tell user that file does not exist */
}