# A Level Computer Science Programming Guide/Arrays

## Declaring Arrays

In Pseudocode, Arrays all have declarable Upper and Lower bounds.

In VB.NET, Arrays all have declarable Upper Bounds, but Lower Bounds are always 0.

### One Dimensional Arrays

Language General Usage Example Usage
Pseudocode
```DECLARE <Identifier> : ARRAY[<Lower Bound>:<Upper Bound>] OF <Data Type>
```
```DECLARE NameList : ARRAY[1:5] OF STRING
DECLARE YearlyRainfall : ARRAY[1900:2100] OF REAL
DECLARE AgeList : ARRAY[0:40] OF INTEGER
```
VB.NET
```Dim <Identifier>(<Upper Bound>) As <Data Type>
```
```Dim NameList(4) As String
Dim YearlyRainfall(200) As Double
Dim AgeList(40) As Integer
```
Python
```<Identifier> = []
```
```NameList = []
YearlyRainfall = []
AgeList = []
```

### Two Dimensional Arrays

Language General Usage Example Usage
Pseudocode
```DECLARE <Identifier> : ARRAY[<Lower Bound>:<Upper Bound>, <Lower Bound>:<Upper Bound>] OF <Data Type>
```
```DECLARE GameArea : ARRAY[1:32, 0:16] OF STRING
DECLARE SudokuGrid : ARRAY[1:9, 1:9] OF INTEGER
DECLARE PopulationDensity : ARRAY[1:50, 20:50] OF REAL
```
VB.NET
```Dim <Identifier>(<Upper Bound>, <Upper Bound>) As <Data Type>
```
```Dim GameArea(31, 16) As String
Dim SudokuGrid(8) As Integer
Dim PopulationDensity(49,30) As Double
```
Python
```<Identifier1> = []
<Identifier2> = []
<Identifier1>.append(<Identifier2>)
```
```Game = []
GameArea = []
GameArea.append(Game)

SudokuX = []
SudokuGrid = []
SudokuGrid.append(SudokuX)

Longitude = []
PopulationDensity = []
PopulationDensity.append(Longitude)
```

## Using Arrays

### One Dimensional Arrays

Language General Usage Example Usage
Pseudocode
```<Identifier>[<Index>] ← <Value>
```
```NameList[1] ← "Stephen"
YearlyRainfall[1985] ← 13.73
AgeList[39] ← 17
```
VB.NET
```<Identifier>(<Index>) = <Value>
```
```NameList(0) = "Stephen"
YearlyRainfall(85) = 13.73
AgeList(38) = 17
```
Python
```<Identifier>.append(<Value>)
```
```NameList.append("Stephen")
YearlyRainfall.append(13.73)
AgeList.append(17)
```

### Two Dimensional Arrays

Language General Usage Example Usage
Pseudocode
```<Identifier>[<Index>,<Index>] ← <Value>
```
```GameArea[16, 5] ← "Fire"
SudokuGrid[9, 3] ← 7
PopulationDensity[14, 32] ← 242.023
```
VB.NET
```<Identifier>(<Index>,<Index>) = <Value>
```
```GameArea(15, 5) = "Fire"
SudokuGrid(8, 2) = 7
PopulationDensity(13, 12) = 242.023
```
Python
```<Identifier1> = []
<Identifier2> = []
<Identifier1>.append(<Identifier2>)
```
```Game.append("Fire")
GameArea.append(Game)

SudokoX.append(7)
SudokuGrid.append(SudokuX)

Longitude.append(242.023)
PopulationDensity.append(Longitude)
```