C的优先级有时候会发生很坑爹的问题- -贴个优先级表方便查看- -
| 有个C的，有个C++的，老实说没发现什么区别- - |
C优先级列表
| **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](http://www.cppreference.com/keywords/sizeof.html) | 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 |
C++优先级列表
| **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](http://www.cppreference.com/keywords/sizeof.html) | 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 | int i = (a > b) ? a : b | left to right |
| 14 | ? : | Ternary conditional (if-then-else) | if( conditionA || conditionB ) ... | 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 |