gtpc2mfeC/C++ Language Support User's Guide

TO2_isEmpty-Test If Collection Is Empty

This function determines if the collection contains any elements.

Format

#include <c$to2.h>
BOOL TO2_isEmpty (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

TO2_IS_FALSE
The collection is not empty.

TO2_IS_TRUE
The collection is empty.

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. This function must also be used with a TO2_IS_FALSE return code to distinguish this return from an error return indication. If the error code returned by TO2_getErrorCode is TO2_IS_FALSE (0), this is the actual return code by the function. Otherwise, an error is indicated. For more information, see Error Handling.

The following error codes are common for this function:

TO2_ERROR_ENV

TO2_ERROR_METHOD

TO2_ERROR_PID

TO2_ERROR_ZERO_PID

Programming Considerations

Examples

The following example tests the cursor to see if the collection contains any elements.

#include <c$to2.h>                   /* Needed for TO2 API Functions    */
#include <stdio.h>                   /* APIs for standard I/O functions */
 
TO2_PID             cursor;
TO2_ENV_PTR         env_ptr;
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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/************************************************************************/ /* Is the cursor pointing to an empty collection? */ /************************************************************************/ if (TO2_isEmpty(&cursor, env_ptr)) == TO2_IS_FALSE) { err_code = TO2_getErrorCode(env_ptr); if (err_code ! = 0) { printf("TO2_isEmpty failed!\n"); process_error(env_ptr); } else printf("The cursor is not pointing to an empty collection!\n"); } else printf("The cursor is pointing to an empty collection.\n");

Related Information

TO2_size-Return the Size of the Collection.