Objective-C教學
Objective-C 教學首頁
Objective-C 語言概述
Objective-C 開發環境(安裝配置)
Objective-C語言程序結構
Objective-C 基本語法
Objective-C 數據類型
Objective-C 變量
Objective-C 常量
Objective-C 運算符
Objective-C 算術運算符
Objective-C 關係運算符
Objective-C 邏輯運算符
Objective-C 位運算符
Objective-C 賦值運算符
Objective-C 循環
Objective-C while循環
Objective-C for循環
Objective-C do...while循環
Objective-C 嵌套循環
Objective-C break語句
Objective-C continue語句
Objective-C 決策
Objective-C if語句
Objective-C if...else 語句
Objective-C 嵌套 if 語句
Objective-C switch語句
Objective-C 嵌套switch語句
Objective-C 函數
Objective-C 函數按值調用
Objective-C 函數引用調用
Objective-C 塊
Objective-C Numbers/數字
Objective-C Arrays/數組
Objective-C 多維數組
Objective-C 數組作爲函數參數傳遞
Objective-C 從函數返回數組
Objective-C 指針的數組
Objective-C 指針
Objective-C 指針運算
Objective-C 數組的指針
Objective-C 指向指針的指針
Objective-C 傳遞函數的指針
Objective-C 函數返回指針
Objective-C NSString/字符串
Objective-C struct/結構
Objective-C 預處理器
Objective-C typedef
Objective-C 類型轉換
Objective-C 日誌處理
Objective-C 錯誤處理
命令行參數
Objective-C 類&對象
Objective-C 繼承
Objective-C 多態性
Objective-C 數據封裝
Objective-C Categories/類別
Objective-C Posing/冒充
Objective-C 擴展
Objective-C Protocols/協議
Objective-C 動態綁定
Objective-C 複合對象
Obj-C Foundation/基礎框架
Objective-C 數據存儲
Objective C 文本和字符串
Objective-C 日期和時間
Objective-C 異常處理
Objective-C 文件處理
Objective-C URL加載系統
Objective-C 快速枚舉
Objective-C 內存管理

Objective-C 邏輯運算符

下表列出了所有支持Objective-C語言的邏輯運算符。假設變量A=1,變量B=0,那麼:

運算符

描述

示例

&&

調用邏輯AND運算符。如果這兩個操作數不爲零,則條件爲真。

(A && B) is false.

||

調用邏輯或運算符。如果兩個操作數中的任何一個不爲零,則條件爲真。

(A || B) is true.

!

調用邏輯NOT運算。使用反轉其操作數的邏輯狀態。如果一個條件是真的,那麼邏輯NOT運算符爲假。

!(A && B) is true.

示例

嘗試下面的例子就明白了所有在Objective-C編程語言的邏輯運算符:

#import <Foundation/Foundation.h> main() { int a = 5; int b = 20; int c ; if ( a && b ) { NSLog(@"Line 1 - Condition is true
" ); } if ( a || b ) { NSLog(@"Line 2 - Condition is true
" ); } /* lets change the value of a and b */ a = 0; b = 10; if ( a && b ) { NSLog(@"Line 3 - Condition is true
" ); } else { NSLog(@"Line 3 - Condition is not true
" ); } if ( !(a && b) ) { NSLog(@"Line 4 - Condition is true
" ); } }

當編譯和執行上述程序,它會產生以下結果:

2013-09-07 22:35:57.256 demo[19012] Line 1 - Condition is true
2013-09-07 22:35:57.256 demo[19012] Line 2 - Condition is true
2013-09-07 22:35:57.256 demo[19012] Line 3 - Condition is not true
2013-09-07 22:35:57.256 demo[19012] Line 4 - Condition is true