Xbasic
Array first_empty Method
Syntax
dim Index as N = <array>.first_empty([C property])
Arguments
- propertyCharacter
If specified, returns the index of the first property that that is undefined for an element in the array.
Returns
- IndexNumeric
Returns the index of the first empty element in the array.
Description
Return the last unused entry in the array.
Discussion
The <array>.first_empty() method returns the index of the first empty element in an array.
Example
Assume an array "A" contains the following elements:
Element | Value |
|---|---|
A[1] | Orange |
A[2] | Banana |
A[3] | Apple |
A[4] | Pineapple |
A[5] | Mango |
A[6] | |
A[7] | |
A[8] |
? A.first_empty() = 6 ' because element 6 is the first NULL (empty) element.
The following example demonstrates using the optional property parameter.
dim trs[10] as p
trs[1].city = "Boston"
trs[1].state = "MA"
trs[2].city = "Attleboro"
trs[2].state = "MA"
trs[3].city = "Providence"
trs[3].state = "RI"
trs[4].city = "Newport"
trs[4].state = ""
trs[5].city = "Barrington"
trs[5].state = ""
? trs.first_empty("state")
= 4If a property is not defined for an element in the array, it will be skipped. In the example above, if state had not been added to trs[4] and trs[5], <array>.first_empty() would return 6, not 4. Therefore, it is important that all elements in the array have the same properties defined.