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Static Arrays
Arrays can be declared in many ways. These first
examples demonstrate arrays that are created at “design time” – (programmer sets
the value(s) and length). This array is “hard coded”. Hard coded means that the
values and length of the array are established at the time the array is declared
and isn’t based on user input or stored data. It won’t vary while the program is
running. Notice that there is more than one way to declare this type of
arrays.
string[] strFruitArray =
{"apple", "banana", "orange", "grape", "pineapple"};
string[] strFruitArray = new
string[]{"apple", "banana", "orange", "grape", "pineapple"};
string[]strFruitArray;
strFruitArray = new string [5]
{"apple", "banana", "orange", "grape", "pineapple"};
Regardless of which method is used to declare the array,
referencing the individual values is done the same way
strFruitArray[0] = “apple”
strFruitArray[1] = “banana”
strFruitArray[2] = “orange”
strFruitArray[3] = “grape”
strFruitArray[4] =
“pineapple”
Dynamic Arrays
Most of the time, we need to have arrays that we won’t
know the values or how many items. The next example is an example of a
completely dynamic array. The only information set at design time is the data
type (int), the variable name (intArray), and that it is an array ([]). The
values and the number of values will be based on user input or data retrieved
from at runtime. The following is an example of how this type of array is
declared.
No length or values set at the time of declaration. Set
this at the class level (see full example download) in order for it to be
visible to the entire form class.
int[] intArray;
Fixed length at the time of declaration but not the
values
intArray = new int[5];
Practical Example of a Dynamic Array
In the example below, there is a list box with some
values. When the user clicks the “Create Array” button, the array size is set to
the number of items in the list box and a for loop is used to add the values to
the dynamic array.
private
void btnCreateArray_Click(object sender, EventArgs e)
{
//the
number of items in the list box is the size of our array.
int
intNumItems = lstBoxValues.Items.Count;//get the number of items
strListItems = new
string[intNumItems];
//use a for
iteration to add the items.
//List
boxes are also 0 based. The first item in the list will be referred to as
lstBoxValues[0].
for (int
intX = 0; intX < lstBoxValues.Items.Count; intX++)
strListItems[intX] =
lstBoxValues.Items[intX].ToString();
//Show
array properties in a rich text box named rtbArrayValues
rtbArrayValues.Text = "Total
number of elements = " + strListItems.LongLength + "\n" ;//the \n is a
return
rtbArrayValues.Text += "The
LowerBound() value = " + strListItems.GetLowerBound(0).ToString() + "\n";
rtbArrayValues.Text += "The
UpperBound() value = " + strListItems.GetUpperBound(0).ToString() + "\n" ;
//show all
of the values using the for iteration
for (int
intX = 0; intX <= strListItems.GetUpperBound(0); intX++)
rtbArrayValues.Text += "value "
+ intX + " is " + strListItems[intX] + "\n";
}
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