obj -c NSArray計數比較失敗

Question

NSArray *test1 = [NSArray arrayWithObjects:@"1",@"2", nil]; 
NSArray *test2 = [NSArray arrayWithObjects:@"1",@"2", nil]; 
NSArray *test3 = [NSArray arrayWithObjects:@"1",@"2", nil]; 

NSLog(@"%d", [test1 count] == [test2 count] == [test3 count]); 

將打印0.爲什麼？

Answer 1

我會推測你的第一個測試[test1 count] == [test2 count]返回true（或1），但第二個測試1 == [test3 count]失敗，因爲它有2個元素。你可能想說（[test1 count] == [test2 count]）& &（[test2 count] == [test3 count]）。在使用的傳遞特性平等的測試 - 也就是說，如果A == B和B == C，則A == C.

Answer 2

[test1 count] == [test2 count] == [test3 count]

會評價：

[test1 count] == [test2 count] == [test3 count] 
= (int of 2) == (int of 2) == [test3 count] 
= (BOOL of YES) == (int of 2) // Comparing an implicit 1 with 2 so != 
= (BOOL of NO) 
= (int of zero implicit cast)