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。
| 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 « typeid(var).name(); cout « 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 |
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