C++ 运算符优先级列表
2010-09-14 13:22
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The operators at the top of this list are evaluated first. Operators within a group have the same precedence. All operators have left-to-right associativity unless otherwise noted.
| Precedence | Operator | Description | Example | Overloadable | Associativity |
|---|---|---|---|---|---|
| 1 | :: | Scope resolution operator | Class::age = 2; | no | left to right |
| 2 | () | Function call | printf(“Hello world/n”); | yes | left to right |
() | 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 | ||
dynamic_cast | Runtime-checked type conversion | Y& y = dynamic_cast<Y&>(x); | no | ||
static_cast | Unchecked type conversion | Y& y = static_cast<Y&>(x); | no | ||
reinterpret_cast | Reinterpreting type conversion | int const* p = reinterpret_cast<int const*>(0x1234); | no | ||
const_cast | Cast away/Add constness | int* q = const_cast<int*>(p); | no | ||
typeid | Get type information | std::type_info const& t = typeid(x); | no | ||
| 3 | ! | Logical negation | if (!done) ... | yes | right to left |
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 | ||
sizeof | Size (of the type) of the operand in bytes | size_t s = sizeof(int); | no | ||
new | Dynamic memory allocation | long* pVar = new long; | yes | ||
new [] | Dynamic memory allocation of array | long* array = new long[20]; | 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 | ||
| 4 | ->* | Member pointer selector | ptr->*var = 24; | yes | left to right |
.* | Member object selector | obj.*var = 24; | no | ||
| 5 | * | Multiplication | int i = 2 * 4; | yes | left to right |
/ | Division | float f = 10.0 / 3.0; | yes | ||
% | Modulus | int rem = 4 % 3; | yes | ||
| 6 | + | Addition | int i = 2 + 3; | yes | left to right |
- | Subtraction | int i = 5 - 1; | yes | ||
| 7 | << | Bitwise shift left | int flags = 33 << 1; | yes | left to right |
>> | Bitwise shift right | int flags = 33 >> 1; | yes | ||
| 8 | < | Comparison less-than | if (i < 42) ... | yes | left to right |
<= | 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 | ||
| 9 | == | Comparison equal-to | if (i == 42) ... | yes | left to right |
eq | Alternate spelling for == | ||||
!= | Comparison not-equal-to | if (i != 42) ... | yes | ||
not_eq | Alternate spelling for != | ||||
| 10 | & | Bitwise AND | flags = flags & 42; | yes | left to right |
bitand | Alternate spelling for & | ||||
| 11 | ^ | Bitwise exclusive OR (XOR) | flags = flags ^ 42; | yes | left to right |
xor | Alternate spelling for ^ | ||||
| 12 | | | Bitwise inclusive (normal) OR | flags = flags | 42; | yes | left to right |
bitor | Alternate spelling for | | ||||
| 13 | && | Logical AND | if (conditionA && conditionB) ... | yes | left to right |
and | Alternate spelling for && | ||||
| 14 | || | Logical OR | if (conditionA || conditionB) ... | yes | left to right |
or | Alternate spelling for || | ||||
| 15 | ? : | Ternary conditional (if-then-else) | int i = a > b ? a : b; | no | right to left |
| 16 | = | Assignment operator | int a = b; | yes | right to left |
+= | 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 | ||
| 17 | throw | throw exception | throw EClass(“Message”); | no | |
| 18 | , | Sequential evaluation operator | for (i = 0, j = 0; i < 10; i++, j++) ... | yes | left to right |
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