02-结构体的几个小应用

1、查找某个字符串在str中的范围 (使用 rangeOfString:@"")

 1 #import <Foundation/Foundation.h>
 2 //查找某个字符串在str中的范围
 3 void test()
 4 {
 5     NSString *str = @"i love you";
 6     NSRange range = [str rangeOfString:@"ov"];
 7     //如果找不到：length = 0, location = NSNotFound = -1
 8     NSRange range1 = [str rangeOfString:@"good"];
 9     NSLog(@"ov.location = %ld, ov.length = %ld", range.location, range.length);
10     //这里location使用%d输出,结果就是-1
11     NSLog(@"good.location = %ld, good.length = %ld", range1.location, range1.length);
12 }
13 int main(int argc, const char * argv[])
14 {
15     test();
16     return 0;
17 }

输出结果：

2、CGRect结构体变量的赋值

 1 #import <Foundation/Foundation.h>
 2 void test()
 3 {
 4     CGPoint p1 = CGPointMake(10, 10);
 5     CGPoint p2 = CGPointMake(20, 20);
 6     CGSize s1 = CGSizeMake(100, 50);
 7     CGSize s2 = CGSizeMake(200, 80);
 8     
 9     CGRect r1 = CGRectMake(0, 0, 100, 50);
10     CGRect r2 = {{0, 0}, {100, 50}};
11     // 在给CGRect变量赋值时，可以直接使用CGPoint变量和CGSize变量
12     CGRect r3 = {p1, s2};
13     NSString *str = NSStringFromRect(r3);
14     NSLog(@"%@", str);
15 }
16 int main(int argc, const char * argv[])
17 {
18     test();
19     return 0;
20 }

当出现第10行这种情况：CGRect r2 = {{0, 0}, {100, 50}}; point坐标为{0, 0}的时候，可以使用CGPointZero来替换。CGPointZero表示的是坐标原点(x==0, y==0)。

代码：

 1 void test1()
 2 {
 3     CGRect r1 = {{0, 0}, {100, 80}};
 4     CGRect r2 = {CGPointZero, {100, 80}};
 5     
 6     NSString *str1 = NSStringFromRect(r1);
 7     NSString *str2 = NSStringFromRect(r2);
 8     NSLog(@"%@", str1);
 9     NSLog(@"%@", str2);
10 }
11 int main(int argc, const char * argv[])
12 {
13     test1();
14     return 0;
15 }

同理，size坐标为{0, 0}等价于CGSizeZero。

综上可知：CGPointZero == CGPointMake(0, 0); 表示坐标原点

　　　　 CGSizeZero == CGSizeMake(0, 0); 表示尺寸为0

　　　　　CGRectZero == CGRectMake(0, 0, 0, 0);

3、利用BOOL CGPointEqualToPoint(CGPoint point1, CGPoint point2) 判断两个点是否是同一个点

代码：

 1 #import <Foundation/Foundation.h>
 2 
 3 int main(int argc, const char * argv[])
 4 {
 5     CGPoint point1 = CGPointMake(10, 10);
 6     CGPoint point2 = CGPointMake(10, 10);
 7     CGPoint point3 = CGPointMake(10, 20);
 8     int a = CGPointEqualToPoint(point1, point2);
 9     int b = CGPointEqualToPoint(point1, point3);
10     NSLog(@"a = %d", a);
11     NSLog(@"b = %d", b);
12     return 0;
13 }

由函数CGPointEqualToPoint(CGPoint point1, CGPoint point2); 可以推知以下函数：

　　CGSizeEqualToSize(CGSize size1, CGSize size2); 判断两个尺寸是否相同

　　CGRectEqualToRect(CGRect rect1, CGRect rect2);

4、利用CGRectContainsPoint(CGRect rect, CGPoint point); 判断一个点是否在一个区域内

 1 //判断一个点是否在一个区域内
 2 void test1()
 3 {
 4     CGRect rect = CGRectMake(40, 30, 100, 50);
 5     CGPoint point = CGPointMake(50, 45);
 6     int s = CGRectContainsPoint(rect, point);
 7     NSLog(@"s = %d", s);
 8 }
 9 int main(int argc, const char * argv[])
10 {
11     test1();
12     return 0;
13 }