c++提供了一元操作符和二元操作符，另外還有三元操作符（三目操作符cond?expr1:exprl2）。
算術運算子
一元正號（+）返回運算元本身，對運算元不做任何修改。
邏輯運算子
存在短路求值。
優先順序表如下：
precedence
operator
description
example
associativity1()
->.::
++--
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 right2!
~++---
+*&(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 right4*
/%multiplication
division
modulus
int i = 2 * 4;
float f = 10 / 3;
int rem = 4 % 3;
left to right5+
-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 right8==
!=comparison equal-to
comparison not-equal-to
if( i == 42 ) ...
if( i != 42 ) ...
left to right9&
bitwise and
flags = flags & 42;
left to right10^
bitwise exclusive or
flags = flags ^ 42;
left to right11|
bitwise inclusive (normal) or
flags = flags | 42;
left to right
12&&
logical and
if( conditiona && conditionb ) ...
left to right
13||
logical or
int i = (a > b) ? a : b
left to right
14? :
ternary conditional (if-then-else)
if( conditiona || conditionb ) ...
right to left15=
+=-=
*=/=
%=&=
^=|=
<<=
>>=
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 left16,
sequential evaluation operator
for( i = 0, j = 0; i < 10; i++, j++ ) ...
left to right
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