Single dimensional Arrays
Arrays are used to store values of similar type. With arrays you can store a sequence of values and refer to them with an index. In .net several inbuilt function makes it easy to manage array values. Let us see the arrays in detail,
Declaring and Initializing single dimensional arrays
Like any other variable you can declare and initialize arrays in same statement. When you declare an array in this way you must specify the type and count of the array elements. Unlike in Visual Basic 6.0, Arrays in .net are zero based. That is by default the first array element have an index 0. So the last element will have an index equal to the total number of elements minus one.
e.g. Dim MyArray(9) as string
MyArray(0) = “Peter”
MyArray(1) = “Tom”
MyArray(2) = “Fred”
MyArray(3) = “Barbara”
The above line will create an array of size 10. Like in Visual Studio 6 you cannot specify a lower bound in an array declaration.
e.g. Dim MyArray() = {“ Peter”,” Tom”,”Nancy”}
The above line will create an array of size 3 with values provided. You can use the Ubound() function to determine the upper bound of the array.
Declaring and Initializing Multi-dimensional arrays
You can declare a multi-dimensional array like this,
Dim MyArray(4,2) as integer
Dim MyArray( , ) as integer = {{1,2,3,4},{5,6,7,8},{9,10,11,12}}
READ VALUES
Dim Counter1 as integer
Dim Counter2 as integer
For counter1 = 0 to ubound(MyArray)
For counter2 = 0 to ubound(MyArray,2)
Debug.writeline MyArray(counter1,counter2).ToString
Next counter2
Next counter1
Dynamic Arrays
Some time we require to populate an array dynamically at runtime. So declaring an array with the limit specified doesn’t help. We need to create an array with the maximum limit specified on the fly. Like in Visual Studio 6.0 you can make use of the Redim statement to declare an array dynamically. But simply using redim will clear the previous values in the array. For that we can use preserve keyword along with the redim statement.
Dim MyArray() as integer
You can make use of the array now as the maximum limit is not specified, If you use a statement like this, it would raise an exception. So before making use of this array, declare it like this
‘Write Values
Dim inc as integer
Inc = 1
For counter = 1 to 100
Redim preserve MyArray(counter) as integer
MyArray(Counter) = inc
Inc += 1
Next
‘Read Values
For counter = 0 to ubound(MyArray)
Debug.writeline MyArray(counter).ToString
Next
The disadvantage with the arrays is that you cannot store different types of values in an array. For this refer the Collections in .net.
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| Author: raja gopal 27 Jun 2004 | Member Level: Bronze Points : 0 |
Article is very good and it gives good knowledge about ARRAYs. I like the way he presented with examples. My intention in giving feed back is to encourage this type of articles.
thanks
raj
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| Author: sridhar venkataramanan 08 Feb 2005 | Member Level: Bronze Points : 0 |
could you spell the short cut way to scroll thru the properties window
of vb.net as that of vb. [ctrl+shift+first character of the property )
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