Objective-C文法之指標型參數

標籤：

main.m

 1 #import <Foundation/Foundation.h> 2 /** 3  *  測試指標型參數和普通參數的區別 4  * 5  *  @param a 指標型參數 6  *  @param b 普通參數 7  * 8  *  @return (指標型參數+2) + (普通參數+2) 9  */10 int pointerTypeParameterTest(int *a, int b) {11     *a = *a + 2; //*a表示擷取a變數指標（記憶體位址）所指向記憶體儲存空間內的值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=0x7fff5fbff79820         NSLog(@"pointerTypeParameterTest(&a, b)=%d", pointerTypeParameterTest(&a, b)); //pointerTypeParameterTest(&a, b)=13；&a表示擷取a變數的記憶體位址，b表示擷取變數的值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=0x7fff5fbff79c27         *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=0x7fff5fbff79c29     }30     return 0;31 }

 

結果：

1 2015-05-09 20:42:11.593 OCPointerTypeParameter[562:21474] a=4, b=5; &a=0x7fff5fbff79c, &b=0x7fff5fbff7982 2015-05-09 20:42:11.594 OCPointerTypeParameter[562:21474] pointerTypeParameterTest(&a, b)=133 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=0x7fff5fbff79c5 2015-05-09 20:42:11.595 OCPointerTypeParameter[562:21474] c=8, a=8; &c=0x7fff5fbff790, c=0x7fff5fbff79c, &a=0x7fff5fbff79c

 

Objective-C文法之指標型參數