Operators in C and C++
This is a list of operators in the C and C++ programming languages. All the operators listed exist in C++; the fourth column "Included in C", states whether an operator is also present in C. Note that C does not support operator overloading.
When not overloaded, for the operators
&&, ||, and ,, there is a sequence point after the evaluation of the first operand.C++ also contains the type conversion operators
const_cast, static_cast, dynamic_cast, and reinterpret_cast. The formatting of these operators means that their precedence level is unimportant.Most of the operators available in C and C++ are also available in other C-family languages such as C#, D, Java, Perl, and PHP with the same precedence, associativity, and semantics.
Table
For the purposes of these tables,a, b, and c represent valid values, object names, or lvalues, as appropriate. R, S and T stand for any type, and K for a class type or enumerated type.Arithmetic operators
Comparison operators/relational operators
Logical operators
Bitwise operators
Compound assignment operators
Member and pointer operators
Other operators
Notes:Operator precedence
The following is a table that lists the precedence and associativity of all the operators in the C and C++ languages. Operators are listed top to bottom, in descending precedence. Descending precedence refers to the priority of the grouping of operators and operands. Considering an expression, an operator which is listed on some row will be grouped prior to any operator that is listed on a row further below it. Operators that are in the same cell are grouped with the same precedence, in the given direction. An operator's precedence is unaffected by overloading.The syntax of expressions in C and C++ is specified by a phrase structure grammar. The table given here has been inferred from the grammar. For the ISO C 1999 standard, section 6.5.6 note 71 states that the C grammar provided by the specification defines the precedence of the C operators, and also states that the operator precedence resulting from the grammar closely follows the specification's section ordering:
"C syntax|The syntax specifies the precedence of operators in the evaluation of an expression, which is the same as the order of the major subclauses of this subclause, highest precedence first."
A precedence table, while mostly adequate, cannot resolve a few details. In particular, note that the ternary operator allows any arbitrary expression as its middle operand, despite being listed as having higher precedence than the assignment and comma operators. Thus
a ? b, c : d is interpreted as a ? : d, and not as the meaningless , . So, the expression in the middle of the conditional operator is parsed as if parenthesized. Also, note that the immediate, unparenthesized result of a C cast expression cannot be the operand of sizeof. Therefore, sizeof * x is interpreted as * x and not sizeof .| Precedence | Operator | Description | Associativity |
| 1 highest | :: | Scope resolution | - |
| 2 | ++ | Postfix increment | Left-to-right |
| 2 | -- | Postfix decrement | Left-to-right |
| 2 | | Function call | Left-to-right |
| 2 | | Array subscripting | Left-to-right |
| 2 | . | Element selection by reference | Left-to-right |
| 2 | -> | Element selection through pointer | Left-to-right |
| 2 | typeid | Run-time type information | Left-to-right |
| 2 | const_cast | Type cast | Left-to-right |
| 2 | dynamic_cast | Type cast | Left-to-right |
| 2 | reinterpret_cast | Type cast | Left-to-right |
| 2 | static_cast | Type cast | Left-to-right |
| 3 | ++ | Prefix increment | Right-to-left |
| 3 | -- | Prefix decrement | Right-to-left |
| 3 | + | Unary plus | Right-to-left |
| 3 | - | Unary minus | Right-to-left |
| 3 | ! | Logical NOT | Right-to-left |
| 3 | ~ | Bitwise NOT | Right-to-left |
| 3 | | Type cast | Right-to-left |
| 3 | * | Indirection | Right-to-left |
| 3 | & | Address-of | Right-to-left |
| 3 | sizeof | Sizeof | Right-to-left |
| 3 | _Alignof | Alignment requirement | Right-to-left |
| 3 | new, new | Dynamic memory allocation | Right-to-left |
| 3 | delete, delete | Dynamic memory deallocation | Right-to-left |
| 4 | .* | Pointer to member | Left-to-right |
| 4 | ->* | Pointer to member | Left-to-right |
| 5 | * | Multiplication | Left-to-right |
| 5 | / | Division | Left-to-right |
| 5 | % | Modulo | Left-to-right |
| 6 | + | Addition | Left-to-right |
| 6 | - | Subtraction | Left-to-right |
| 7 | << | Bitwise left shift | Left-to-right |
| 7 | >> | Bitwise right shift | Left-to-right |
| 8 | <=> | Three-way comparison | Left-to-right |
| 9 | < | Less than | Left-to-right |
| 9 | <= | Less than or equal to | Left-to-right |
| 9 | > | Greater than | Left-to-right |
| 9 | >= | Greater than or equal to | Left-to-right |
| 10 | | Equal to | Left-to-right |
| 10 | != | Not equal to | Left-to-right |
| 11 | & | Bitwise AND | Left-to-right |
| 12 | ^ | Bitwise XOR | Left-to-right |
| 13 | | Bitwise OR | Left-to-right |
| 14 | && | Logical AND | Left-to-right |
| 15 | | Logical OR | Left-to-right |
| 16 | ?: | Ternary conditional | Right-to-left |
| 16 | = | Direct assignment | Right-to-left |
| 16 | += | Assignment by sum | Right-to-left |
| 16 | -= | Assignment by difference | Right-to-left |
| 16 | *= | Assignment by product | Right-to-left |
| 16 | /= | Assignment by quotient | Right-to-left |
| 16 | %= | Assignment by remainder | Right-to-left |
| 16 | <<= | Assignment by bitwise left shift | Right-to-left |
| 16 | >>= | Assignment by bitwise right shift | Right-to-left |
| 16 | &= | Assignment by bitwise AND | Right-to-left |
| 16 | ^= | Assignment by bitwise XOR | Right-to-left |
| 16 | | Assignment by bitwise OR | Right-to-left |
| 16 | throw | Throw operator | Right-to-left |
| 17 lowest | , | Comma | Left-to-right |
Criticism of bitwise and equality operators precedence
The precedence of the bitwise logical operators has been criticized. Conceptually, & and | are arithmetic operators like * and +.The expression is syntactically parsed as whereas the expression is parsed as. This requires parentheses to be used more often than they otherwise would.
Historically, there was no syntactic distinction between the bitwise and logical operators. In BCPL, B and early C, the operators didn't exist. Instead had different meaning depending on whether they are used in a 'truth-value context'. It was retained so as to keep backward compatibility with existing installations.
Moreover, in C++ equality operations, with the exception of the three-way comparison operator, yield bool type values which are conceptually a single bit and as such do not properly belong in "bitwise" operations.
C++ operator synonyms
C++ defines certain keywords to act as aliases for a number of operators:| Keyword | Operator |
&& | |
&= | |
& | |
| | |
~ | |
! | |
!= | |
|| | |
|= | |
^ | |
^= |
These can be used exactly the same way as the punctuation symbols they replace, as they are not the same operator under a different name, but rather simple token replacements for the name of the respective operator. This means that the expressions and have identical meanings. It also means that, for example, the
bitand keyword may be used to replace not only the bitwise-and operator but also the address-of operator, and it can even be used to specify reference types. The ISO C specification makes allowance for these keywords as preprocessor macros in the header file iso646.h|. For compatibility with C, C++ provides the header ciso646|, the inclusion of which has no effect.