1 << 1的值是多少？怎么计算呢？

Question

谁能告诉我如何计算1<<0和其他人的价值？我是iOS的新手,我很难理解它.

 kSCNetworkReachabilityFlagsTransientConnection = 1<<0,
  kSCNetworkReachabilityFlagsReachable      = 1<<1,
  kSCNetworkReachabilityFlagsConnectionRequired = 1<<2,
  kSCNetworkReachabilityFlagsConnectionOnTraffic    = 1<<3,
  kSCNetworkReachabilityFlagsInterventionRequired   = 1<<4,
  kSCNetworkReachabilityFlagsConnectionOnDemand = 1<<5, // 

Answer 1

这只是一个移位操作.

1 << 0 = 1
1 << 1 = 2
1 << 2 = 4
1 << 3 = 8
etc...

或者在二进制视图中

00000001 << 1 = 00000010
00000001 << 2 = 00000100
00000001 << 3 = 00001000