Format
#include <recio.h>
_RIOFB_T *_Rreadnc(_RFILE *fp, void *buf, size_t size);Language Level: ILE C Extension
Threadsafe: No.
Description
The _Rreadnc() function reads the next changed record from the current position in the subfile that is associated with fp. The minimum size of data that is read from the screen are copied from the system buffer to buf.
The following are valid parameters for the _Rreadnc() function.
The _Rreadnc() function is valid for subfiles.
Return Value
The _Rreadnc() function returns a pointer to the _RIOFB_T structure that is associated with fp. If the _Rreadnc() operation is successful the num_bytes field is set to the number of bytes transferred from the system buffer to the user's buffer (move mode) or the record length of the file (locate mode). The rrn and sysparm fields are updated. If there are no changed records between the current position and the end of the file, the num_bytes field is set to EOF. If it is unsuccessful, the num_bytes field is set to a value less than size, and errno is changed.
The value of errno may be set to:
See Table 12 and Table 14 for errno settings.
Example that uses _Rreadnc()
#include <stdio.h>
#include <stdlib.h>
#include <recio.h>
#define LEN 10
#define NUM_RECS 20
#define SUBFILENAME "MYLIB/T1677RD6"
#define PFILENAME "MYLIB/T1677RDB"
typedef struct {
char name[LEN];
char phone[LEN];
} pf_t;
#define RECLEN sizeof(pf_t)
void init_subfile(_RFILE *, _RFILE *);
int main(void)
{
_RFILE *pf;
_RFILE *subf;
/*************************************************
* Open the subfile and the physical file. *
*************************************************/
if ((pf = _Ropen(PFILENAME, "rr")) == NULL) {
printf("can't open file %s\n", PFILENAME);
exit(1);
}
if ((subf = _Ropen(SUBFILENAME, "ar+")) == NULL) {
printf("can't open file %s\n", SUBFILENAME);
exit(2);
}
/*************************************************
* Initialize the subfile with records *
* from the physical file. *
*************************************************/
init_subfile(pf, subf);
/*************************************************
* Write the subfile to the display by writing *
* a record to the subfile control format. *
*************************************************/
_Rformat(subf, "SFLCTL");
_Rwrite(subf, "", 0);
_Rreadnc(subf, "", 0);
/*************************************************
* Close the physical file and the subfile. *
*************************************************/
_Rclose(pf);
_Rclose(subf);
}Related Information