gtpc2mfkC/C++ Language Support User's Guide

TO2_next-Increment and Return the Next Element

This function returns the next element in the collection and points the cursor at that element. The definition of the next element depends on the collection implementation.

Format

#include <c$to2.h>
TO2_BUF_PTR TO2_next (const TO2_PID_PTR cursorPidPtr,
                            TO2_ENV_PTR env_ptr);

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.

Normal Return

For a normal return, this buffer contains a C header file followed by a copy of the data requested. The normal return is a pointer (TO2_BUF_PTR) to a structure (buffer) of type TO2_BUF_HDR (see Type Definitions).

Error Return

An error return is indicated by a zero. When zero 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_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 returns the next element in the collection that the cursor points to.

#include <c$to2.h>                /* Needed for TO2 API Functions     */
#include <stdio.h>                /* APIs for standard I/O functions  */
 
struct person_record
{
  char             *name;
  char             *address;
};
typedef struct person_record PERSON_RECORD;
 
TO2_PID             cursor;       /* PID of the cursor                */
TO2_ENV_PTR         env_ptr;      /* Pointer to TO2 environment       */
TO2_BUF_PTR         buffer_ptr;   /* Pointer to element buffer        */
PERSON_RECORD      *person_ptr;   /* Pointer to element data          */
TO2_ERR_CODE        err_code;     /* TO2 error code value             */
TO2_ERR_TEXT_PTR    err_text_ptr; /* TO2 error code text pointer      */

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/**********************************************************************/ /* Access and return the next item the cursor points to. */ /**********************************************************************/ if ((buffer_ptr = TO2_next(&cursor, env_ptr)) == NULL) { err_code = TO2_getErrorCode(env_ptr); if (err_code != TO2_ERROR_EODAD) { printf("TO2_next failed!\n"); process_error(env_ptr); } else printf("The cursor is at the end of the collection!\n"); return(0); } else { person_ptr = (PERSON RECORD *) buffer_ptr->data; printf("TO2_next successful!\n"); }
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free(buffer_ptr);

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