Objective-C语法之指针型参数

main.m

 1 #import <Foundation/Foundation.h>
 2 /**
 3  *  测试指针型参数和普通参数的区别
 4  *
 5  *  @param a 指针型参数
 6  *  @param b 普通参数
 7  *
 8  *  @return (指针型参数+2) + (普通参数+2)
 9  */
10 int pointerTypeParameterTest(int *a, int b) {
11     *a = *a + 2; //*a表示获取a变量指针（内存地址）所指向内存存储空间内的值
12     b = b + 2;
13     return *a+b;
14 }
15 int main(int argc, const char * argv[]) {
16     @autoreleasepool {
17         int a = 4;
18         int b = 5;
19         NSLog(@"a=%d, b=%d; &a=%p, &b=%p", a, b, &a, &b); //a=4, b=5; &a=0x7fff5fbff79c, &b=0x7fff5fbff798
20         NSLog(@"pointerTypeParameterTest(&a, b)=%d", pointerTypeParameterTest(&a, b)); //pointerTypeParameterTest(&a, b)=13；&a表示获取a变量的内存地址，b表示获取变量的值
21         NSLog(@"a=%d, b=%d; &a=%p, &b=%p, after the operation of pointerTypeParameterTest(&a, b)", a, b, &a, &b); //a=6, b=5; &a=0x7fff5fbff79c, &b=0x7fff5fbff798, after the operation of pointerTypeParameterTest(&a, b)
22
23
24         int *c;
25         c = &a;
26         NSLog(@"c=%d, a=%d; &c=%p, c=%p, &a=%p", *c, a, &c, c, &a); //c=6, a=6; &c=0x7fff5fbff790, c=0x7fff5fbff79c, &a=0x7fff5fbff79c
27         *c = 8;
28         NSLog(@"c=%d, a=%d; &c=%p, c=%p, &a=%p", *c, a, &c, c, &a); //c=8, a=8; &c=0x7fff5fbff790, c=0x7fff5fbff79c, &a=0x7fff5fbff79c
29     }
30     return 0;
31 }

结果：

1 2015-05-09 20:42:11.593 OCPointerTypeParameter[562:21474] a=4, b=5; &a=0x7fff5fbff79c, &b=0x7fff5fbff798
2 2015-05-09 20:42:11.594 OCPointerTypeParameter[562:21474] pointerTypeParameterTest(&a, b)=13
3 2015-05-09 20:42:11.594 OCPointerTypeParameter[562:21474] a=6, b=5; &a=0x7fff5fbff79c, &b=0x7fff5fbff798, after the operation of pointerTypeParameterTest(&a, b)
4 2015-05-09 20:42:11.594 OCPointerTypeParameter[562:21474] c=6, a=6; &c=0x7fff5fbff790, c=0x7fff5fbff79c, &a=0x7fff5fbff79c
5 2015-05-09 20:42:11.595 OCPointerTypeParameter[562:21474] c=8, a=8; &c=0x7fff5fbff790, c=0x7fff5fbff79c, &a=0x7fff5fbff79c