下表列出了所有支持Objective-C语言的逻辑运算符。假设变量A=1,变量B=0,那么: 运算符 | 描述 | 示例 | && | 调用逻辑AND运算符。如果这两个操作数不为零,则条件为真。 | (A && B) is false. | || | 调用逻辑或运算符。如果两个操作数中的任何一个不为零,则条件为真。 | (A || B) is true. | ! | 调用逻辑NOT运算。使用反转其操作数的逻辑状态。如果一个条件是真的,那么逻辑NOT运算符为假。 | !(A && B) is true. | 示例尝试下面的例子就明白了所有在Objective-C编程语言的逻辑运算符: #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" ); }} 当编译和执行上述程序,它会产生以下结果: 2013-09-07 22:35:57.256 demo[19012] Line 1 - Condition is true2013-09-07 22:35:57.256 demo[19012] Line 2 - Condition is true2013-09-07 22:35:57.256 demo[19012] Line 3 - Condition is not true2013-09-07 22:35:57.256 demo[19012] Line 4 - Condition is true |