发布于 2015-07-05 11:55:16 | 84 次阅读 | 评论: 0 | 来源: 网络整理
下表列出了所有支持Objective-C语言的关系运算符。假设变量A=10和变量B=20，则：
| 运算符 | 描述 | 示例 |
|---|---|---|
| == | 检查是否两个操作数的值等于或不等于，如果是的话那么条件为真。 | (A == B) is not true. |
| != | 检查两个操作数的值等于或不相等，如果值不相等，则条件为真。 | (A != B) is true. |
| > | 检查是否左操作数的值大于右操作数的值，如果是的话那么条件为真。 | (A > B) is not true. |
| < | 检查是否左操作数的值小于右操作数的值，如果是的话那么条件为真。 | (A < B) is true. |
| >= | 检查是否左操作数的值大于或等于右操作数的值，如果是的话那么条件为真。 | (A >= B) is not true. |
| <= | 检查是否左操作数的值小于或等于右边的操作数的值，如果是的话那么条件为真。 | (A <= B) is true. |
尝试下面的例子就明白了在Objective-C编程语言的所有关系运算符：
#import <Foundation/Foundation.h>
main()
{
int a = 21;
int b = 10;
int c ;
if( a == b )
{
NSLog(@"Line 1 - a is equal to bn" );
}
else
{
NSLog(@"Line 1 - a is not equal to bn" );
}
if ( a < b )
{
NSLog(@"Line 2 - a is less than bn" );
}
else
{
NSLog(@"Line 2 - a is not less than bn" );
}
if ( a > b )
{
NSLog(@"Line 3 - a is greater than bn" );
}
else
{
NSLog(@"Line 3 - a is not greater than bn" );
}
/* Lets change value of a and b */
a = 5;
b = 20;
if ( a <= b )
{
NSLog(@"Line 4 - a is either less than or equal to bn" );
}
if ( b >= a )
{
NSLog(@"Line 5 - b is either greater than or equal to bn" );
}
}
当编译和执行上述程序，它会产生以下结果：
2013-09-07 22:42:18.254 demo[9486] Line 1 - a is not equal to b
2013-09-07 22:42:18.254 demo[9486] Line 2 - a is not less than b
2013-09-07 22:42:18.254 demo[9486] Line 3 - a is greater than b
2013-09-07 22:42:18.254 demo[9486] Line 4 - a is either less than or equal to b
2013-09-07 22:42:18.254 demo[9486] Line 5 - b is either greater than or equal to b