Objective-C语法之指针型参数

main.m

 #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 + ; //*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 + ;
     return *a+b;
 }
 int main(int argc, const char * argv[]) {
     @autoreleasepool {
         int a = ;
         int b = ;
         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 = ;
         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 ;
 }

结果：

 -- ::11.593 OCPointerTypeParameter[:] a=, b=; &a=0x7fff5fbff79c, &b=0x7fff5fbff798
 -- ::11.594 OCPointerTypeParameter[:] pointerTypeParameterTest(&a, b)=
 -- ::11.594 OCPointerTypeParameter[:] a=, b=; &a=0x7fff5fbff79c, &b=0x7fff5fbff798, after the operation of pointerTypeParameterTest(&a, b)
 -- ::11.594 OCPointerTypeParameter[:] c=, a=; &c=0x7fff5fbff790, c=0x7fff5fbff79c, &a=0x7fff5fbff79c
 -- ::11.595 OCPointerTypeParameter[:] c=, a=; &c=0x7fff5fbff790, c=0x7fff5fbff79c, &a=0x7fff5fbff79c