C/C++知识补充(2) C/C++操作符/运算符的优先级 & 结合性

优先级	操作符	描述	例子	结合性
1	() [] -> . :: ++ --	调节优先级的括号操作符 数组下标访问操作符 通过指向对象的指针访问成员的操作符 通过对象本身访问成员的操作符 作用域操作符 后置自增操作符 后置自减操作符	(a + b) / 4; array[4] = 2; ptr->age = 34; obj.age = 34; Class::age = 2; for( i = 0; i < 10; i++ ) ... for( i = 10; i > 0; i-- ) ...	从左到右
2	! ~ ++ -- - + * & (type) sizeof	逻辑取反操作符 按位取反(按位取补) 前置自增操作符 前置自减操作符 一元取负操作符 一元取正操作符 解引用操作符 取地址操作符 类型转换操作符 返回对象占用的字节数操作符	if( !done ) ... flags = ~flags; for( i = 0; i < 10; ++i ) ... for( i = 10; i > 0; --i ) ... int i = -1; int i = +1; data = *ptr; address = &obj; int i = (int) floatNum; int size = sizeof(floatNum);	从右到左
3	->* .*	在指针上通过指向成员的指针访问成员的操作符 在对象上通过指向成员的指针访问成员的操作符	ptr->*var = 24; obj.*var = 24;	从左到右
4	* / %	乘法操作符 除法操作符 取余数操作符	int i = 2 * 4; float f = 10 / 3; int rem = 4 % 3;	从左到右
5	+ -	加法操作符 减法操作符	int i = 2 + 3; int i = 5 - 1;	从左到右
6	<< >>	按位左移操作符 按位右移操作符	int flags = 33 << 1; int flags = 33 >> 1;	从左到右
7	< <= > >=	小于比较操作符 小于或等于比较操作符 大于比较操作符 大于或等于比较操作符	if( i < 42 ) ... if( i <= 42 ) ... if( i > 42 ) ... if( i >= 42 ) ...	从左到右
8	== !=	等于比较操作符 不等于比较操作符	if( i == 42 ) ... if( i != 42 ) ...	从左到右
9	&	按位与操作符	flags = flags & 42;	从左到右
10	^	按位异或操作符	flags = flags ^ 42;	从左到右
11	|	按位或操作符	flags = flags | 42;	从左到右
12	&&	逻辑与操作符	if( conditionA && conditionB ) ...	从左到右
13	||	逻辑或操作符	if( conditionA || conditionB ) ...	从左到右
14	? :	三元条件操作符	int i = (a > b) ? a : b;	从右到左
15	= += -= *= /= %= &= ^= |= <<= >>=	赋值操作符 复合赋值操作符(加法) 复合赋值操作符(减法) 复合赋值操作符(乘法) 复合赋值操作符(除法) 复合赋值操作符(取余) 复合赋值操作符(按位与) 复合赋值操作符(按位异或) 复合赋值操作符(按位或) 复合赋值操作符(按位左移) 复合赋值操作符(按位右移)	int a = b; a += 3; b -= 4; a *= 5; a /= 2; a %= 3; flags &= new_flags; flags ^= new_flags; flags |= new_flags; flags <<= 2; flags >>= 2;	从右到左
16	,	逗号操作符	for( i = 0, j = 0; i < 10; i++, j++ ) ...	从左到右

 

Precedence	Operator	Description	Example	Associativity
1	() [] -> . :: ++ --	Grouping operator Array access Member access from a pointer Member access from an object Scoping operator Post-increment Post-decrement	(a + b) / 4; array[4] = 2; ptr->age = 34; obj.age = 34; Class::age = 2; for( i = 0; i < 10; i++ ) ... for( i = 10; i > 0; i-- ) ...	left to right
2	! ~ ++ -- - + * & (type) sizeof	Logical negation Bitwise complement Pre-increment Pre-decrement Unary minus Unary plus Dereference Address of Cast to a given type Return size in bytes	if( !done ) ... flags = ~flags; for( i = 0; i < 10; ++i ) ... for( i = 10; i > 0; --i ) ... int i = -1; int i = +1; data = *ptr; address = &obj; int i = (int) floatNum; int size = sizeof(floatNum);	right to left
3	->* .*	Member pointer selector Member pointer selector	ptr->*var = 24; obj.*var = 24;	left to right
4	* / %	Multiplication Division Modulus	int i = 2 * 4; float f = 10 / 3; int rem = 4 % 3;	left to right
5	+ -	Addition Subtraction	int i = 2 + 3; int i = 5 - 1;	left to right
6	<< >>	Bitwise shift left Bitwise shift right	int flags = 33 << 1; int flags = 33 >> 1;	left to right
7	< <= > >=	Comparison less-than Comparison less-than-or-equal-to Comparison greater-than Comparison geater-than-or-equal-to	if( i < 42 ) ... if( i <= 42 ) ... if( i > 42 ) ... if( i >= 42 ) ...	left to right
8	== !=	Comparison equal-to Comparison not-equal-to	if( i == 42 ) ... if( i != 42 ) ...	left to right
9	&	Bitwise AND	flags = flags & 42;	left to right
10	^	Bitwise exclusive OR	flags = flags ^ 42;	left to right
11	|	Bitwise inclusive (normal) OR	flags = flags | 42;	left to right
12	&&	Logical AND	if( conditionA && conditionB ) ...	left to right
13	||	Logical OR	if( conditionA || conditionB ) ...	left to right
14	? :	Ternary conditional (if-then-else)	int i = (a > b) ? a : b;	right to left
15	= += -= *= /= %= &= ^= |= <<= >>=	Assignment operator Increment and assign Decrement and assign Multiply and assign Divide and assign Modulo and assign Bitwise AND and assign Bitwise exclusive OR and assign Bitwise inclusive (normal) OR and assign Bitwise shift left and assign Bitwise shift right and assign	int a = b; a += 3; b -= 4; a *= 5; a /= 2; a %= 3; flags &= new_flags; flags ^= new_flags; flags |= new_flags; flags <<= 2; flags >>= 2;	right to left
16	,	Sequential evaluation operator	for( i = 0, j = 0; i < 10; i++, j++ ) ...	left to right