Swift 2.0学习笔记（Day 46）——下标重写

class DoubleDimensionalArray {     

    let rows: Int, columns: Int

    var grid: [Int]   

    init(rows: Int, columns: Int) {

        self.rows = rows

        self.columns = columns

        grid = Array(count: rows * columns, repeatedValue: 0)

    }  

    subscript(row: Int, col: Int) -> Int {    //定义下标       

        get {
            return grid[(row * columns) + col]
        }       

        set {
            grid[(row * columns) + col] = newValue
        }
    }                     //定义下标  

}

class SquareMatrix: DoubleDimensionalArray {   

    override subscript(row: Int, col: Int) -> Int {   //重写父类下标      

        get {     

            return super.grid[(row * columns) + col]   
        } 
        set {  
            super.grid[(row * columns) + col] = newValue * newValue
        } 
    }
} 
var ary2 = SquareMatrix(rows: 5, columns: 5) 
for var i = 0; i < 5; i++ {
    for var j = 0; j < 5; j++ {
        ary2[i,j] = i + j
    }} 
for var i = 0; i < 5; i++ {
    for var j = 0; j < 5; j++ {
        print("\t\t \(ary2[i,j])")
    }
    print("\n")
}