在一个表达式中可能包含多个有不同运算符连接起来的、具有不同数据类型的数据对象；由于表达式有多种运算，不同的运算顺序可能得出不同结果甚至出现错误运算错误，因为当表达式中含多种运算时，必须按一定顺序进行结合，才能保证运算的合理性和结果的正确性、唯一性。
优先级从上到下依次递减，最上面具有最高的优先级，逗号操作符具有最低的优先级。表达式的结合次序取决于表达式中各种运算符的优先级。优先级高的运算符先结合，优先级低的运算符后结合，同一行中的运算符的优先级相同。
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Operator
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Description
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Example
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Overloadable
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Group 1(no associativity)
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|||
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::
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Scope resolution operator
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Class::age = 2;
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NO
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Group 2
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|||
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()
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Function call
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isdigit('1')
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YES
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()
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Member initalization
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c_tor(int x, int y) : _x(x), _y(y*10){};
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YES
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[]
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Array access
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array[4] = 2;
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YES
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->
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Member access from a pointer
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ptr->age = 34;
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YES
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.
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Member access from an object
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obj.age = 34;
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NO
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++
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Post-increment
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for( int i = 0; i < 10; i++ ) cout << i;
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YES
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--
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Post-decrement
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for( int i = 10; i > 0; i-- ) cout << i;
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YES
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const_cast
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Special cast
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const_cast<type_to>(type_from);
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NO
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dynamic_cast
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Special cast
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dynamic_cast<type_to>(type_from);
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NO
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static_cast
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Special cast
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static_cast<type_to>(type_from);
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NO
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reinterpret_cast
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Special cast
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reinterpret_cast<type_to>(type_from);
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NO
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typeid
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Runtime type information
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cout « typeid(var).name();
cout « typeid(type).name();
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NO
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Group 3(right-to-left associativity)
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|||
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!
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Logical negation
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if( !done ) …
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YES
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not
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Alternate spelling for !
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||
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~
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Bitwise complement
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flags = ~flags;
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YES
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compl
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Alternate spelling for ~
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||
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++
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Pre-increment
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for( i = 0; i < 10; ++i ) cout << i;
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YES
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--
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Pre-decrement
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for( i = 10; i > 0; --i ) cout << i;
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YES
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-
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Unary minus
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int i = -1;
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YES
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+
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Unary plus
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int i = +1;
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YES
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|
*
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Dereference
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int data = *intPtr;
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YES
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|
&
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Address of
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int *intPtr = &data;
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YES
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new
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Dynamic memory allocation
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long *pVar = new long;
MyClass *ptr = new MyClass(args);
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YES
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new []
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Dynamic memory allocation of array
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long *array = new long[n];
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YES
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delete
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Deallocating the memory
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delete pVar;
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YES
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delete []
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Deallocating the memory of array
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delete [] array;
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YES
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|
(type)
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Cast to a given type
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int i = (int) floatNum;
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YES
|
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sizeof
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Return size of an object or type
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int size = sizeof floatNum;
int size = sizeof(float);
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NO
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Group 4
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|||
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->*
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Member pointer selector
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ptr->*var = 24;
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YES
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.*
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Member object selector
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obj.*var = 24;
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NO
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|
Group 5
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|||
|
*
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Multiplication
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int i = 2 * 4;
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YES
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|
/
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Division
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float f = 10.0 / 3.0;
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YES
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%
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Modulus
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int rem = 4 % 3;
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YES
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Group 6
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|||
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+
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Addition
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int i = 2 + 3;
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YES
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-
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Subtraction
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int i = 5 - 1;
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YES
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Group 7
|
|||
|
<<
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Bitwise shift left
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int flags = 33 << 1;
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YES
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>>
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Bitwise shift right
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int flags = 33 >> 1;
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YES
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|
Group 8
|
|||
|
<
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Comparison less-than
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if( i < 42 ) …
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YES
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<=
|
Comparison less-than-or-equal-to
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if( i <= 42 ) ...
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YES
|
|
>
|
Comparison greater-than
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if( i > 42 ) …
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YES
|
|
>=
|
Comparison greater-than-or-equal-to
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if( i >= 42 ) ...
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YES
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|
Group 9
|
|||
|
==
|
Comparison equal-to
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if( i == 42 ) ...
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YES
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|
eq
|
Alternate spelling for ==
|
||
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!=
|
Comparison not-equal-to
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if( i != 42 ) …
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YES
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not_eq
|
Alternate spelling for !=
|
||
|
Group 10
|
|||
|
&
|
Bitwise AND
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flags = flags & 42;
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YES
|
|
bitand
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Alternate spelling for &
|
||
|
Group 11
|
|||
|
^
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Bitwise exclusive OR (XOR)
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flags = flags ^ 42;
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YES
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|
xor
|
Alternate spelling for ^
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||
|
Group 12
|
|||
|
|
|
Bitwise inclusive (normal) OR
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flags = flags | 42;
|
YES
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|
bitor
|
Alternate spelling for |
|
||
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Group 13
|
|||
|
&&
|
Logical AND
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if( conditionA && conditionB ) …
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YES
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|
and
|
Alternate spelling for &&
|
||
|
Group 14
|
|||
|
||
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Logical OR
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if( conditionA || conditionB ) ...
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YES
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|
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
|
作者：耑新新，发布于 博客园
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