An array is an indexed collection of elements. The array will have an identifier and elements will be indexed by integers:

   Stock
0. PollenFilter
1. OilFilter
2. AirFilter
3. FuelFilter
4. HydraulicFilter
5. WaterFilter

The element at Stock[4] is a string variable with the value of "HydraulicFilter". The index range for C++ invariably forces the use of 0 as the start point of an array.

Type	Identifier	Description
Array of string	Stock[6]	An array holding stock names

Data table entry for an array

In C++ the declaration is:

   AnsiString Stock[6];

The base type is declared followed by the identifier and the array size.

Arrays must have the following properties:

• A fixed number of elements
• Elements of the same base type

There are no operations allowed directly on whole arrays:

• No assignment MyArray = YourArray is illegal
• No assignment MyArray = 0 is illegal
• No comparison MyArray == YourArray is illegal

Comparing arrays for equality can only be done through the individual comparison of each pair of corresponding elements.

Tables

One method of collating records into larger structures is via an 'array of records'. All the constituent elements of the array must be of the same type. This same type includes structured (programmer defined). An array of records is a table.

Stock

Index	Item	Unit	Cost
0	Oil	Litre	1.58
1	OilFilter	Each	3.35
2	AirFilter	Each	5.32
3	FuelFilter	Each	7.07
4	HydraulicFilter	Each	12.05

There are three fields, each with identifiers with index numbers in the left hand column. In C++ it is declared as follows:

struct	StockType
{
 AnsiString		Item;
 AnsiString		Unit;
 float		Cost;
};
StockType Stock[5];

Two-dimensional arrays

Type	Identifier	Description
Array of character	Page[40][80]	A two-dimensional array of characters

Data table entry for a two-dimensional array

Here an array of arrays is created showing the equivalent of 40 lines of text on a page with 80 characters per line. In C++:

char Page[40][80];

Accessing is by:

Page[Row][Column];

Once declared the order of the indexes is fixed. The form for declaring a two-dimensional array is therefore:

BaseType   ArrayName   [FirstIndexSize][SecondIndexSize];

Identified by:

ArrayName[FirstIndex][SecondIndex];

Comments, suggestions, ideas to
Stuart Banner