对象作为函数参数

//  对象作为函数的参数--类与对象的内存分析
//成员方法和函数的区别
#import <Foundation/Foundation.h>

@interface Car : NSObject{
    @public
    int wheel;
    int speed;
}
-(void) run;
@end

@implementation Car
-(void)run{
    NSLog(@"%i轮子，时速%i的车子跑起来了",wheel,speed);
}
@end

//函数一：这种情况，c->wheel的值传进来了，并不会影响对象成员变量的值
void test(int m,int s){
    m=20;
    s=300;
}

//函数二：这种情况能够改变对象的值
void test1(Car* mc){
    mc->wheel=5;
}

//函数三：这种情况不会改变
void test2(Car* mc){
    Car *c2 = [Car new];
    c2->wheel = 5;
    c2->speed = 300;

    mc = c2;
    mc->wheel = 6;
}

int main(int argc, const char * argv[]) {

    Car* c=[Car new];

    c->wheel=4;
    c->speed=200;

//    test(c->wheel,c->speed);
    test1(c);

    [c run];
    return 0;
}