Objective-C 賦值運算符

支持Objective-C語言的賦值運算符有以下：

運算符

描述說明

示例

=

Simple assignment operator, Assigns values from right side operands to left side operand

C = A + B will assign value of A + B into C

+=

Add AND assignment operator, It adds right operand to the left operand and assigns the result to left operand

C += A 等同於 C = C + A

-=

Subtract AND assignment operator, It subtracts right operand from the left operand and assigns the result to left operand

C -= A 等同於 C = C - A

*=

Multiply AND assignment operator, It multiplies right operand with the left operand and assigns the result to left operand

C *= A 等同於 C = C * A

/=

Divide AND assignment operator, It divides left operand with the right operand and assigns the result to left operand

C /= A 等同於 C = C / A

%=

Modulus AND assignment operator, It takes modulus using two operands and assigns the result to left operand

C %= 等同於 C = C % A

<<=

Left shift AND assignment operator

C <<= 2 等同於 C = C << 2

>>=

Right shift AND assignment operator

C >>= 2 等同於 C = C >> 2

&=

Bitwise AND assignment operator

C &= 2 等同於C = C & 2

^=

bitwise exclusive OR and assignment operator

C ^= 2 等同於C = C ^ 2

|=

bitwise inclusive OR and assignment operator

C |= 2 等同於 C = C | 2

例子

嘗試下面的例子就明白了所有在Objective-C編程語言的賦值運算符：

#import <Foundation/Foundation.h> main() { int a = 21; int c ; c = a; NSLog(@"Line 1 - = Operator Example, Value of c = %d
", c ); c += a; NSLog(@"Line 2 - += Operator Example, Value of c = %d
", c ); c -= a; NSLog(@"Line 3 - -= Operator Example, Value of c = %d
", c ); c *= a; NSLog(@"Line 4 - *= Operator Example, Value of c = %d
", c ); c /= a; NSLog(@"Line 5 - /= Operator Example, Value of c = %d
", c ); c = 200; c %= a; NSLog(@"Line 6 - %= Operator Example, Value of c = %d
", c ); c <<= 2; NSLog(@"Line 7 - <<= Operator Example, Value of c = %d
", c ); c >>= 2; NSLog(@"Line 8 - >>= Operator Example, Value of c = %d
", c ); c &= 2; NSLog(@"Line 9 - &= Operator Example, Value of c = %d
", c ); c ^= 2; NSLog(@"Line 10 - ^= Operator Example, Value of c = %d
", c ); c |= 2; NSLog(@"Line 11 - |= Operator Example, Value of c = %d
", c ); }

當編譯和執行上述程序，它會產生以下結果：

2013-09-07 22:00:19.263 demo[21858] Line 1 - = Operator Example, Value of c = 21
2013-09-07 22:00:19.263 demo[21858] Line 2 - += Operator Example, Value of c = 42
2013-09-07 22:00:19.263 demo[21858] Line 3 - -= Operator Example, Value of c = 21
2013-09-07 22:00:19.263 demo[21858] Line 4 - *= Operator Example, Value of c = 441
2013-09-07 22:00:19.263 demo[21858] Line 5 - /= Operator Example, Value of c = 21
2013-09-07 22:00:19.264 demo[21858] Line 6 - %= Operator Example, Value of c = 11
2013-09-07 22:00:19.264 demo[21858] Line 7 - <<= Operator Example, Value of c = 44
2013-09-07 22:00:19.264 demo[21858] Line 8 - >>= Operator Example, Value of c = 11
2013-09-07 22:00:19.264 demo[21858] Line 9 - &= Operator Example, Value of c = 2
2013-09-07 22:00:19.264 demo[21858] Line 10 - ^= Operator Example, Value of c = 0
2013-09-07 22:00:19.264 demo[21858] Line 11 - |= Operator Example, Value of c = 2