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Array Declaration and Built-in Functions
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(Continued from previous part...)
Assigning Values to Array Elements
New values can be assigned to individual elements in an array using assignment statements like this:
array_variable(index) = new_value
where "index" is the index value of an element the array associated with "array_variable", and
"new_value" is the new value to be assigned the array element. The data type of the new value must
match the array data type.
Retrieving Values from Array Elements
Retrieving values from array elements can done through their indexes like this:
... = ... array_variable(index) ...
VB also offers a special loop statement, "For Each" statement, to retrieve every element in an array like this:
For Each element_variable In array_variable
... = ... element_variable ...
Next
This statement will iterate through every element in the specified array. At each interation,
The value of the current element will be copied to the specified temporary variable, "element_variable".
The order of iteration is based on element index values from the lower bound to the upper bound.
Fixed-Size Array Example
To show you how fixed size array works, I wrote the following example, array_fixed_size.html:
<html>
<body>
<!-- array_fixed_size.html
Copyright (c) 2006 by Dr. Herong Yang. http://www.herongyang.com/
-->
<pre>
<script language="vbscript">
document.writeln("")
Dim aWeek(6)
document.writeln("Is aWeek an array? " & IsArray(aWeek))
aWeek(0) = "Sun"
aWeek(4) = "Thu"
aWeek(6) = "Sat"
aWeek(1) = "Mon"
document.writeln("Days in a week:")
For i=LBound(aWeek) To UBound(aWeek)
document.writeln(" " & i & " = " & aWeek(i))
Next
' aWeek(10) = "Abc" 'Error 1: Subscription out of range
' ReDim Preserve aWeek(10) 'Error 2: This array is fixed
</script>
</pre>
</body>
</html>
Here is the output:
Is aWeek an array? True
Days in a week:
0 = Sun
1 = Mon
2 =
3 =
4 = Thu
5 =
6 = Sat
Note that there are two errors commented out in the example:
- Error 1 - Array index (subscription) must be in the range of lower bound and upper bound.
- Error 2 - Fixed-size array can not be resized with "ReDim" statements.
(Continued on next part...)
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