Objective-C语法之指针型参数

#import <Foundation/Foundation.h>
/**
*  测试指针型参数和普通参数的区别
*
*  @param a 指针型参数
*  @param b 普通参数
*
*  @return (指针型参数+2) + (普通参数+2)
*/
int pointerTypeParameterTest(int *a, int b) {
*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
b = b + 2;
return *a+b;
}
int main(int argc, const char * argv[]) {
@autoreleasepool {
int a = 4;
int b = 5;
NSLog(@"a=%d, b=%d; &a=%p, &b=%p", a, b, &a, &b); //a=4, b=5; &a=0x7fff5fbff79c, &b=0x7fff5fbff798
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
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)

int *c;
c = &a;
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
*c = 8;
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
}
return 0;
}

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