Swift 循环(for ,while, do..while)

Swift.png

for循环

• 常见的写法

//传统的写法，已经在Swift 3中移除了额，这种写法是错误的

//for var i = 0; i < 10; i += 1 {
//    
//    print(i);
//}

//在swift中 for循环 要使用区间，之前的写法不在适用了
//正确的写法
for i in 0..<10 {
    print(i);
}

// _代表忽略的意思  区间遍历
for _ in 0..<10 {
    print("zaza");
}



var numbers = ["cc","ss","dd"]

for i in 0 ..< numbers.count {
   print(numbers[i]);
}


//反向遍历 
 let testArray = ["1","2","3","4"];
        
        for i in testArray.reversed() {
            
            print(i)
        }

//打印结果: 4,3,2,1

while循环

var i = 10;
//条件必须为真才执行
while i > 0 {
    i -= 1;
    print(i);
}

repeat...while循环 代替 do..while

• 注意 在swift中 do..while循环已经被 repeat...while 代替，原因：do在swift有特殊的含义

  
  do..while.jpg

var i = 5;

repeat{
    i += 1;
    print(i);

} while i < 10