設定運算子

1. 設定運算子 (Assignment Operators) 說明：
   

   運算子	描述	例子
   =	將右邊的值設定給左邊的變數	C=A+B
   +=	將右邊的值加到左邊的變數	C+=A, C=C+A
   -=	將左邊的變數減去右邊的值	C-=A, C=C-A
   *=	將左邊的變數乘以右邊的值	C*=A, C=C*A
   /=	將左邊的變數除以右邊的值	C/=A, C=C/A
   %=	左邊的變數為左邊變數除右邊變數取餘數	C%=A, C=C%A
   <<=	左邊變數 left shift 右邊值	C<<2, C=C<<2
   >>=	左邊變數 right shift 右邊值	C>>2, C=C>>2
   &=	左邊變數 bitwise AND 右邊值	C&=2, C=C&2
   ^=	左邊變數 bitwise exclusive OR 右邊值	C^=2, C=C^2
   |=	左邊變數 bitwise OR 右邊值	C|=2, C=C|2

2. 範例程式

   [dywang@deyu zzz]$ vim op-as1.c 
   [dywang@deyu zzz]$ cat op-as1.c 
   #include <stdio.h>
   
   int main() {
       int a, c;
   
       printf("Enter an integer: ");
       scanf("%d", &a);
   
       c = a;
       printf("c = a, c = %d\n", c );
   
       c += a;
       printf("c += a, c = %d\n", c );
   
       c -= a;
       printf("c -= a, c = %d\n", c );
       
       c *= a;
       printf("c *= a, c = %d\n", c );
       
       c /= a;
       printf("c /= a, c = %d\n", c );
       
       c = 200;
       c %= a;
       printf("c = 200\nc %= a, c = %d\n", c );
   
       a <<= 2;
       printf("a <<= 2, a = %d\n", a );
       
       a >>= 2;
       printf("a >>= 2, a = %d\n", a );
       
       a &= 2;
       printf("a &= 2, a = %d\n", a );
       
       a ^= 2;
       printf("a ^= 2, a = %d\n", a );
   
       a |= 2;
       printf("a |= 2, a = %d\n", a );
   }
   

3. 編譯成功

   [dywang@deyu zzz]$ gcc -o op-as1 op-as1.c
   

4. 執行結果

   [dywang@deyu zzz]$ ./op-as1 
   Enter an integer: 21
   c = a, c = 21
   c += a, c = 42
   c -= a, c = 21
   c *= a, c = 441
   c /= a, c = 21
   c = 200
   c %= a, c = 11
   a <<= 2, a = 84
   a >>= 2, a = 21
   a &= 2, a = 0
   a ^= 2, a = 2
   a |= 2, a = 2