Can someone explain how to declare a 2 dimensional array and how to populate a few entries. Google was not useful.
A two-dimensional array is just an Array
of Array
s:
let arr: [[Int]] = [[0,1,2], [10,20,30], [200,300,400]]
print(arr[1][0]) //10
An intriguing alternative is this Matrix
struct given in the Swift Language Guide:
struct Matrix {
let rows: Int, columns: Int
var grid: [Double]
init(rows: Int, columns: Int) {
self.rows = rows
self.columns = columns
grid = Array(repeating: 0.0, count: rows * columns)
}
func indexIsValid(row: Int, column: Int) -> Bool {
return row >= 0 && row < rows && column >= 0 && column < columns
}
subscript(row: Int, column: Int) -> Double {
get {
assert(indexIsValid(row: row, column: column), "Index out of range")
return grid[(row * columns) + column]
}
set {
assert(indexIsValid(row: row, column: column), "Index out of range")
grid[(row * columns) + column] = newValue
}
}
}
You access its elements like so:
matrix[0, 1] = 1.5
matrix[1, 0] = 3.2