I have found it useful from time to time to have a function that will set the internal pointer of an array to a particular key position. I therefore propose the addition of the following function:

mixed setpos(array array, mixed keyval)

The function merely sets the internal pointer of the array to the element referenced by keyval, and returns the value of the element at that position.

I have included what I believe is source code that should add the functionality, though it is untested. I have included only the actual C code, but I think the header file lines to be added are pretty obvious. 

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ADDITIONS TO /EXT/STANDARD/ARRAY.C:
-----------------------------------

/* {{{ proto mixed setpos(array array_arg, mixed keyval)
   Set array argument's internal pointer to the element indexed by keyval and return it */	
PHP_FUNCTION(setpos)
{
	pval **array, **entry;
	HashTable *target_hash;

	if (ZEND_NUM_ARGS() != 2 || zend_get_parameters_ex(2, &array) == FAILURE) {
		WRONG_PARAM_COUNT;
	}
	target_hash = HASH_OF(*array);
	if (!target_hash) {
		php_error(E_WARNING, "Variable passed to setpos() is not an array or object");
		RETURN_FALSE;
	}
	if(Z_TYPE_PP(keyval) == IS_LONG)
		zend_hash_internal_pointer_index_set(target_hash, keyval);
	else if(Z_TYPE_PP(keyval) == IS_STRING)
		zend_hash_internal_pointer_set(target_hash, keyval, Z_STRLEN_PP(keyval)+1);
	else {
		php_error(E_WARNING, "Can only have STRING and INTEGER keys!");
	}

	if (return_value_used) {	
		if (zend_hash_get_current_data(target_hash, (void **) &entry) == FAILURE) {
			RETURN_FALSE;
		}

		*return_value = **entry;
		zval_copy_ctor(return_value);
	}
}
/* }}} */

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ADDITIONS TO /ZEND/ZEND_HASH.C:
-------------------------------


/* Returns SUCCESS if found and FAILURE if not. If the key is found, the internal pointer is set to point at that element. */
ZEND_API int zend_internal_pointer_set(HashTable *ht, char *arKey, uint nKeyLength)
{
	ulong h;
	uint nIndex;
	Bucket *p;

	IS_CONSISTENT(ht);

	HANDLE_NUMERIC(arKey, nKeyLength, zend_internal_pointer_index_set(ht, idx));

	h = ht->pHashFunction(arKey, nKeyLength);
	nIndex = h % ht->nTableSize;

	p = ht->arBuckets[nIndex];
	while (p != NULL) {
		if ((p->h == h) && (p->nKeyLength == nKeyLength)) {
			if (!memcmp(p->arKey, arKey, nKeyLength)) {
				ht->pInternalPointer = p;
				return SUCCESS;
			}
		}
		p = p->pNext;
	}
	return FAILURE;
}


ZEND_API int zend_internal_pointer_index_set(HashTable *ht, ulong h)
{
	uint nIndex;
	Bucket *p;

	IS_CONSISTENT(ht);

	nIndex = h % ht->nTableSize;

	p = ht->arBuckets[nIndex];
	while (p != NULL) {
		if ((p->h == h) && (p->nKeyLength == 0)) {
			ht->pInternalPointer = p;
			return SUCCESS;
		}
		p = p->pNext;
	}
	return FAILURE;
}