Objective-c-sizeof-operator

Objective-Cのsizeofおよび三項演算子

*sizeof* や*？など、他の重要な演算子はほとんどありません。 ：* Objective-C言語でサポートされています。

Operator	Description	Example
sizeof()	Returns the size of an variable.	sizeof(a), where a is integer, will return 4.
&	Returns the address of an variable.	&a; will give actual address of the variable.
*	Pointer to a variable.	*a; will pointer to a variable.
? :	Conditional Expression	If Condition is true ? Then value X : Otherwise value Y

例

次の例を試して、Objective-Cプログラミング言語で使用できるその他の演算子をすべて理解してください-

#import <Foundation/Foundation.h>

int main() {
   int a = 4;
   short b;
   double c;
   int* ptr;

  /*example of sizeof operator*/
   NSLog(@"Line 1 - Size of variable a = %d\n", sizeof(a) );
   NSLog(@"Line 2 - Size of variable b = %d\n", sizeof(b) );
   NSLog(@"Line 3 - Size of variable c= %d\n", sizeof(c) );

  /*example of & and* operators */
   ptr = &a;   /* 'ptr' now contains the address of 'a'*/
   NSLog(@"value of a is  %d\n", a);
   NSLog(@"*ptr is %d.\n", *ptr);

  /*example of ternary operator*/
   a = 10;
   b = (a == 1) ? 20: 30;
   NSLog(@"Value of b is %d\n", b );

   b = (a == 10) ? 20: 30;
   NSLog(@"Value of b is %d\n", b );
}

上記のプログラムをコンパイルして実行すると、次の結果が生成されます-

2013-09-07 22:46:22.702 demo[24593] Line 1 - Size of variable a = 4
2013-09-07 22:46:22.703 demo[24593] Line 2 - Size of variable b = 2
2013-09-07 22:46:22.703 demo[24593] Line 3 - Size of variable c= 8
2013-09-07 22:46:22.703 demo[24593] value of a is  4
2013-09-07 22:46:22.703 demo[24593] *ptr is 4.
2013-09-07 22:46:22.703 demo[24593] Value of b is 30
2013-09-07 22:46:22.703 demo[24593] Value of b is 20