C++运算符优先级

Posted 2020-06-19 随风飘落的雨滴

 

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

 

 

 

 

Operator	Description	Example	Overloadable
Group 1(no associativity)
::	Scope resolution operator	Class::age = 2;	NO
Group 2
()	Function call	isdigit(‘1‘)	YES
()	Member initalization	c_tor(int x, int y) : _x(x), _y(y*10){};	YES
[]	Array access	array[4] = 2;	YES
->	Member access from a pointer	ptr->age = 34;	YES
.	Member access from an object	obj.age = 34;	NO
++	Post-increment	for( int i = 0; i < 10; i++ ) cout << i;	YES
--	Post-decrement	for( int i = 10; i > 0; i-- ) cout << i;	YES
const_cast	Special cast	const_cast<type_to>(type_from);	NO
dynamic_cast	Special cast	dynamic_cast<type_to>(type_from);	NO
static_cast	Special cast	static_cast<type_to>(type_from);	NO
reinterpret_cast	Special cast	reinterpret_cast<type_to>(type_from);	NO
typeid	Runtime type information	cout &laquo; typeid(var).name(); cout &laquo; typeid(type).name();	NO
Group 3(right-to-left associativity)
!	Logical negation	if( !done ) …	YES
not	Alternate spelling for !
~	Bitwise complement	flags = ~flags;	YES
compl	Alternate spelling for ~
++	Pre-increment	for( i = 0; i < 10; ++i ) cout << i;	YES
--	Pre-decrement	for( i = 10; i > 0; --i ) cout << i;	YES
-	Unary minus	int i = -1;	YES
+	Unary plus	int i = +1;	YES
*	Dereference	int data = *intPtr;	YES
&	Address of	int *intPtr = &data;	YES
new	Dynamic memory allocation	long *pVar = new long; MyClass *ptr = new MyClass(args);	YES
new []	Dynamic memory allocation of array	long *array = new long[n];	YES
delete	Deallocating the memory	delete pVar;	YES
delete []	Deallocating the memory of array	delete [] array;	YES
(type)	Cast to a given type	int i = (int) floatNum;	YES
sizeof	Return size of an object or type	int size = sizeof floatNum; int size = sizeof(float);	NO
Group 4
->*	Member pointer selector	ptr->*var = 24;	YES
.*	Member object selector	obj.*var = 24;	NO
Group 5
*	Multiplication	int i = 2 * 4;	YES
/	Division	float f = 10.0 / 3.0;	YES
%	Modulus	int rem = 4 % 3;	YES
Group 6
+	Addition	int i = 2 + 3;	YES
-	Subtraction	int i = 5 - 1;	YES
Group 7
<<	Bitwise shift left	int flags = 33 << 1;	YES
>>	Bitwise shift right	int flags = 33 >> 1;	YES
Group 8
<	Comparison less-than	if( i < 42 ) …	YES
<=	Comparison less-than-or-equal-to	if( i <= 42 ) ...	YES
>	Comparison greater-than	if( i > 42 ) …	YES
>=	Comparison greater-than-or-equal-to	if( i >= 42 ) ...	YES
Group 9
==	Comparison equal-to	if( i == 42 ) ...	YES
eq	Alternate spelling for ==
!=	Comparison not-equal-to	if( i != 42 ) …	YES
not_eq	Alternate spelling for !=
Group 10
&	Bitwise AND	flags = flags & 42;	YES
bitand	Alternate spelling for &
Group 11
^	Bitwise exclusive OR (XOR)	flags = flags ^ 42;	YES
xor	Alternate spelling for ^
Group 12
|	Bitwise inclusive (normal) OR	flags = flags | 42;	YES
bitor	Alternate spelling for |
Group 13
&&	Logical AND	if( conditionA && conditionB ) …	YES
and	Alternate spelling for &&
Group 14
||	Logical OR	if( conditionA || conditionB ) ...	YES
or	Alternate spelling for ||
Group 15(right-to-left associativity)
? :	Ternary conditional (if-then-else)	int i = (a > b) ? a : b;	NO
Group 16(right-to-left associativity)
=	Assignment operator	int a = b;	YES
+=	Increment and assign	a += 3;	YES
-=	Decrement and assign	b -= 4;	YES
*=	Multiply and assign	a *= 5;	YES
/=	Divide and assign	a /= 2;	YES
%=	Modulo and assign	a %= 3;	YES
&=	Bitwise AND and assign	flags &= new_flags;	YES
and_eq	Alternate spelling for &=
^=	Bitwise exclusive or (XOR) and assign	flags ^= new_flags;	YES
xor_eq	Alternate spelling for ^=
|=	Bitwise normal OR and assign	flags |= new_flags;	YES
or_eq	Alternate spelling for |=
<<=	Bitwise shift left and assign	flags <<= 2;	YES
>>=	Bitwise shift right and assign	flags >>= 2;	YES
Group 17
throw	throw exception	throw EClass(“Message”);	NO
Group 18
,	Sequential evaluation operator	for( i = 0, j = 0; i < 10; i++, j++ ) …	YES