Visual Basic.NET How to Program (PDF)

Chapter 7 Arrays 247
location or element in an array, we specify the name of the array and the position number
of the element to which we refer. Position numbers are values that indicate specific locations
within arrays.
Figure 7.1 depicts an integer array named numberArray. This array contains 12 elements,
any one of which can be referred to by giving the name of the array followed by the
position number of the element in parentheses (). The first element in every array is the
zeroth element. Thus, the first element of array numberArray is referred to as number-
Array(0), the second element of array numberArray is referred to as number-
Array(1), the seventh element of array numberArray is referred to as
numberArray(6) and so on. The ith element of array numberArray is referred to as
numberArray(i - 1).
The position number in parentheses more formally is called an index (or a subscript).
An index must be an integer or an integer expression. If a program uses an expression as an
index, the expression is evaluated first to determine the index. For example, if variable
value1 is equal to 5, and variable value2 is equal to 6, then the statement
numberArray(value1 + value2) += 2
adds 2 to array element numberArray(11). Note that an indexed array name (i.e., the
array name followed by an index enclosed in parentheses) is an lvalue—it can be used on
the left side of an assignment statement to place a new value into an array element.
Name of array (note
that all elements of this
array have the same
name, numberArray)
Position number (index or
subscript) of the element
within array numberArray
numberArray(0)
numberArray(1)
numberArray(2)
numberArray(3)
numberArray(4)
numberArray(5)
numberArray(6)
numberArray(7)
numberArray(8)
numberArray(9)
numberArray(10)
numberArray(11)
Fig. Fig. 7.1 7.1 Array consisting of 12 elements.
-45
6
0
72
1543
-89
0
62
-3
1
6453
78