Swift_下标

Swift_下标

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func testSubscripts() {
    
    //下标关键字subscript
    //array测试
    struct TestArray {
        
        //内部数组
        var array = Array<Int>()
        
        //下标使用
        subscript(index: Int) -> Int {
            get {
                assert(index < array.count, "下标越界")
                return array[index]
            }
            set {
                while array.count <= index {
                    array.append(0)
                }
                array[index] = newValue
            }
        }
    }
    
    var array = TestArray()
    
    array[3] = 4; //经过下标设置值
    
    print(array)
    
    print("\(array[3])") //4
    print("\(array[4])") //程序中止
}