Objective-C 中的关系运算符
下表显示了 Objective-C 语言支持的所有关系运算符。 假设变量A为10，变量B为20，则 −
| 运算符 | 描述 | 示例 |
|---|---|---|
| == | 检查两个操作数的值是否相等； 如果是，则条件变为真。 | (A == B) 不为 true |
| != | 检查两个操作数的值是否相等； 如果值不相等，则条件为真。 | (A != B) 为 true |
| > | 检查左操作数的值是否大于右操作数的值； 如果是，则条件变为真。 | (A > B) 不为 true |
| < | 检查左操作数的值是否小于右操作数的值； 如果是，则条件变为真。 | (A < B) 为 true |
| >= | 检查左操作数的值是否大于或等于右操作数的值； 如果是，则条件变为真。 | (A >= B) 不为 true |
| <= | 检查左操作数的值是否小于或等于右操作数的值； 如果是，则条件变为真。 | (A <= B) 为 true |
示例
尝试以下示例来理解 Objective-C 编程语言中可用的所有关系运算符 −
#import <Foundation/Foundation.h>
int main() {
int a = 21;
int b = 10;
if( a == b ) {
NSLog(@"Line 1 - a is equal to b\n" );
} else {
NSLog(@"Line 1 - a is not equal to b\n" );
}
if ( a < b ) {
NSLog(@"Line 2 - a is less than b\n" );
} else {
NSLog(@"Line 2 - a is not less than b\n" );
}
if ( a > b ) {
NSLog(@"Line 3 - a is greater than b\n" );
} else {
NSLog(@"Line 3 - a is not greater than b\n" );
}
/* 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 b\n" );
}
if ( b >= a ) {
NSLog(@"Line 5 - b is either greater than or equal to b\n" );
}
}
当你编译并执行上面的程序时，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
objective_c_operators.html
