gtpc2mf2C/C++ Language Support User's Guide

TO2_atCursorWithBuffer-Return the Element Pointed to by the Cursor

This function returns the element pointed to by the cursor in the specified buffer.

Format

#include <c$to2.h>
TO2_BUF_PTR TO2_atCursorWithBuffer (const TO2_PID_PTR  cursorPidPtr
                                          TO2_ENV_PTR  env_ptr,
                                    const long        *bufferLength,
                                          void        *bufferPtr

cursorPidPtr
The pointer to the cursor persistent identifier (PID) created by one of the TPF collection support (TPFCS) create cursor application programming interfaces (APIs).

env_ptr
The pointer to the environment as returned by the TO2_createEnv function.

bufferLength
The pointer to the length of the specified buffer. The buffer should be large enough to hold the data to be returned plus 16 additional bytes for a header. The minimum buffer length is 20 bytes.

bufferPtr
The pointer to the buffer where the element will be returned.

Normal Return

The normal return is a pointer (TO2_BUF_PTR) to a structure (buffer) of type TO2_BUF_HDR (see Type Definitions). If the length of the data is greater than the length of the buffer, only the amount of data that will fit is placed in the buffer. The actual length of the data element is returned in the dataL field of the buffer. Check the returned length against the length of the supplied buffer to determine if the entire element has been returned.

Error Return

An error return is indicated by NULL. When NULL is returned, use the TO2_getErrorCode function to determine the specific error code. For more information, see Error Handling.

The following error codes are common for this function:

TO2_ERROR_BUFFER_SIZE

TO2_ERROR_CURSOR

TO2_ERROR_EMPTY

TO2_ERROR_ENV

TO2_ERROR_EODAD

TO2_ERROR_METHOD

TO2_ERROR_PID

TO2_ERROR_ZERO_PID

Programming Considerations

Examples

The following example reads the item that the cursor is currently pointing to and returns it in the supplied buffer.

#include <c$to2.h>                /* Needed for TO2 API Functions     */
#include <stdio.h>                /* APIs for standard I/O functions  */
 
struct person_record
{
  char              name[20];
  char              address[50];
};
typedef struct person_record PERSON_RECORD;
 
TO2_PID             cursor;       /* Pointer to cursor                */
TO2_ENV_PTR         env_ptr;      /* Pointer to TO2 environment       */
TO2_BUF_PTR         buffer_ptr;   /* Pointer to collection element    */
long                buffer_length;/* Total length of the buffer area  */
PERSON_RECORD      *person_ptr;   /* Pointer to element data          */
TO2_ERR_CODE        err_code;     /* TO2 error code value             */

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/**********************************************************************/ /* Read the item that the cursor is currently pointing to */ /* and return it in the supplied buffer. */ /**********************************************************************/ buffer_length = sizeof(TO2_BUF_HDR) + sizeof(PERSON_RECORD); if ((buffer_ptr=malloc(buffer_length)) == NULL) { printf("malloc() failed!\n"); return(0); } if ((buffer_ptr=TO2_atCursorWithBuffer(&cursor, env_ptr, &buffer_length, buffer_ptr)) == NULL) { err_code = TO2_getErrorCode(env_ptr); if (err_code != TO2_ERROR_EODAD) { printf("TO2_atCursorWithBuffer failed!\n"); process_error(env_ptr); } else printf("TO2_atCursor is at the end of the data!\n"); } else { person_ptr = buffer_ptr->data; if (buffer_ptr->dataL < (sizeof(TO2_BUF_HDR) + sizeof(PERSON_RECORD)) printf("Data returned did not fit in allocated buffer!\n"); else printf("TO2_atCursorWithBuffer successful!\n"); }

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