[問題] 程式碼問題有關NSSet

看板MacDev作者dreambegins ( ′-`)時間5年前 (2019/05/01 15:14)推噓2(2推 0噓 5→)

留言7則, 4人參與討論串1/1

不好意思直接貼上上色過程太麻煩可怕了如果可以麻煩大大也直接複製貼上到編輯器跑結果我的第二個問題是結果無法理解 #import <Foundation/Foundation.h> // Create an integer object #define INTOBJ(v) [NSNumber numberWithInteger: v] // Add a print method to NSSet with the Printing category @interface NSSet (Printing)<=====我想問的第一個問題，括號這個是什麼？ -(void) print; @end @implementation NSSet (Printing) -(void) print { printf ("{ "); for (NSNumber *element in self) printf (" %li ", (long) [element integerValue]); printf ("} \n"); } @end int main (int argc, char * argv[]) { @autoreleasepool { NSMutableSet *set1 = [NSMutableSet setWithObjects: INTOBJ(1), INTOBJ(3), INTOBJ(5), INTOBJ(10), nil]; NSSet *set2 = [NSSet setWithObjects: INTOBJ(-5), INTOBJ(100), INTOBJ(3), INTOBJ(5), nil]; NSSet *set3 = [NSSet setWithObjects: INTOBJ(12), INTOBJ(200), INTOBJ(3), nil]; NSLog(@"set1: "); [set1 print];<=====我想問的第三個問題 NSLog(@"set2: "); [set2 print]; // Equality test if ([set1 isEqualToSet: set2] == YES) NSLog (@"set1 equals set2"); else NSLog (@"set1 is not equal to set2"); // Membership test if ([set1 containsObject: INTOBJ(10)] == YES) NSLog (@"set1 contains 10"); else NSLog (@"set1 does not contain 10"); if ([set2 containsObject: INTOBJ(10)] == YES) NSLog (@"set2 contains 10"); else NSLog (@"set2 does not contain 10"); // add and remove objects from mutable set set1 [set1 addObject: INTOBJ(4)]; [set1 removeObject: INTOBJ(10)]; NSLog (@"set1 after adding 4 and removing 10: "); [set1 print]; // get intersection of two sets [set1 intersectSet: set2]; NSLog (@"set1 intersect set2: "); [set1 print]; // union of two sets [set1 unionSet:set3]; NSLog (@"set1 union set3: "); [set1 print]; <=====我想問的第二個問題 } return 0; } 這本書是精通Obj C...作者提供的討論區已經404 not found了...QQ 所以上來求救第一個問題：(printing) 的寫法是什麼意思？書本上根本就沒交代清楚第二個問題：書上寫的結果是 set1 union set3: { 12 3 5 200 } 我覺得很奇怪，union的數學意義不是聯集嗎？為什麼結果不是{ 1 3 4 5 12 200 }？第三個問題：為什麼印出這些元素的時候沒按照順序啊？本來就隨便排序的嗎？以上麻煩大大謝謝！ -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 39.9.168.193 ※ 文章網址: https://www.ptt.cc/bbs/MacDev/M.1556694862.A.48B.html ※ 編輯: dreambegins (39.9.168.193), 05/01/2019 15:16:07

[問題] 程式碼問題 有關NSSet

[問題] 程式碼問題有關NSSet