C# Run Thread Again After Catching Fire
This is a listing of operators in the C and C++ programming languages. All the operators listed be in C++; the column "Included in C", states whether an operator is besides present in C. Notation that C does not support operator overloading.
When non overloaded, for the operators &&
, ||
, and ,
(the comma operator), there is a sequence point after the evaluation of the first operand.
C++ also contains the blazon conversion operators const_cast
, static_cast
, dynamic_cast
, and reinterpret_cast
. The formatting of these operators ways 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 [edit]
For the purposes of these tables, a
, b
, and c
represent valid values (literals, values from variables, or render value), object names, or lvalues, equally appropriate. R
, S
and T
stand for any blazon(s), and 1000
for a form type or enumerated type.
Arithmetic operators [edit]
All arithmetic operators be in C and C++ and tin can exist overloaded in C++.
Operator name | Syntax | C++ paradigm examples | ||
---|---|---|---|---|
Every bit member of One thousand | Exterior grade definitions | |||
Addition | a + b | R K :: operator + ( South b ); | R operator + ( Grand a , Due south b ); | |
Subtraction | a - b | R Yard :: operator - ( S b ); | R operator - ( Chiliad a , S b ); | |
Unary plus (integer promotion) | +a | R K :: operator + (); | R operator + ( Thou a ); | |
Unary minus (additive inverse) | -a | R Grand :: operator - (); | R operator - ( K a ); | |
Multiplication | a * b | R K :: operator * ( S b ); | R operator * ( K a , Due south b ); | |
Division | a / b | R Yard :: operator / ( S b ); | R operator / ( M a , Due south b ); | |
Modulo (integer remainder)[a] | a % b | R One thousand :: operator % ( S b ); | R operator % ( K a , S b ); | |
Increase | Prefix | ++a | R & K :: operator ++ (); | R & operator ++ ( K & a ); |
Postfix | a++ | R G :: operator ++ ( int ); | R operator ++ ( K & a , int ); | |
Notation: C++ uses the unnamed dummy-parameter int to differentiate between prefix and postfix increment operators. | ||||
Decrement | Prefix | --a | R & Chiliad :: operator -- (); | R & operator -- ( K & a ); |
Postfix | a-- | R M :: operator -- ( int ); | R operator -- ( K & a , int ); | |
Note: C++ uses the unnamed dummy-parameter int to differentiate between prefix and postfix decrement operators. |
Comparison operators/relational operators [edit]
All comparing operators tin be overloaded in C++.
Operator name | Syntax | Included in C | Image examples | ||
---|---|---|---|---|---|
As member of K | Exterior grade definitions | ||||
Equal to | a == b | Yes | bool K :: operator == ( S const & b ) const ; | bool operator == ( K const & a , South const & b ); | |
Not equal to | a != b a not_eq b [b] | Yes | bool One thousand :: operator != ( Southward const & b ) const ; | bool operator != ( K const & a , S const & b ); | |
Greater than | a > b | Yes | bool K :: operator > ( S const & b ) const ; | bool operator > ( K const & a , S const & b ); | |
Less than | a < b | Aye | bool M :: operator < ( S const & b ) const ; | bool operator < ( K const & a , S const & b ); | |
Greater than or equal to | a >= b | Yes | bool One thousand :: operator >= ( Due south const & b ) const ; | bool operator >= ( K const & a , S const & b ); | |
Less than or equal to | a <= b | Yes | bool K :: operator <= ( S const & b ) const ; | bool operator <= ( K const & a , Southward const & b ); | |
Three-style comparison[c] | a <=> b | No | machine M :: operator <=> ( const S & b ); | auto operator <=> ( const K & a , const S & b ); | |
The operator has a full of 3 possible return types: std::weak_ordering , std::strong_ordering and std::partial_ordering to which they all are convertible to. |
Logical operators [edit]
All logical operators exist in C and C++ and can be overloaded in C++, albeit the overloading of the logical AND and logical OR is discouraged, considering as overloaded operators they behave as ordinary part calls, which means that both of their operands are evaluated, then they lose their well-used and expected short-circuit evaluation property.[1]
Operator name | Syntax | C++ prototype examples | ||
---|---|---|---|---|
As member of One thousand | Outside course definitions | |||
Logical negation (NOT) | !a not a [b] | bool K :: operator ! (); | bool operator ! ( M a ); | |
Logical AND | a && b a and b [b] | bool Thousand :: operator && ( S b ); | bool operator && ( K a , South b ); | |
Logical OR | a || b a or b [b] | bool M :: operator || ( S b ); | bool operator || ( K a , South b ); |
Bitwise operators [edit]
All bitwise operators exist in C and C++ and can be overloaded in C++.
Operator name | Syntax | Prototype examples | ||
---|---|---|---|---|
Every bit member of Thousand | Exterior class definitions | |||
Bitwise Not | ~a compl a [b] | R Yard :: operator ~ (); | R operator ~ ( K a ); | |
Bitwise AND | a & b a bitand b [b] | R Grand :: operator & ( Due south b ); | R operator & ( K a , Due south b ); | |
Bitwise OR | a | b a bitor b [b] | R K :: operator | ( S b ); | R operator | ( K a , S b ); | |
Bitwise XOR | a ^ b a xor b [b] | R K :: operator ^ ( S b ); | R operator ^ ( Thou a , S b ); | |
Bitwise left shift[d] | a << b | R 1000 :: operator << ( South b ); | R operator << ( M a , Due south b ); | |
Bitwise right shift[d] [e] | a >> b | R Yard :: operator >> ( South b ); | R operator >> ( K a , Southward b ); |
Assignment operators [edit]
All assignment expressions exist in C and C++ and tin can be overloaded in C++.
For the given operators the semantic of the built-in combined assignment expression a ⊚= b
is equivalent to a = a ⊚ b
, except that a
is evaluated just once.
Operator proper name | Syntax | C++ prototype examples | |
---|---|---|---|
As member of K | Outside grade definitions | ||
Directly assignment | a = b | R & K :: operator = ( S b ); | N/A |
Addition consignment | a += b | R & K :: operator += ( S b ); | R & operator += ( Yard & a , South b ); |
Subtraction consignment | a -= b | R & K :: operator -= ( S b ); | R & operator -= ( M & a , Due south b ); |
Multiplication assignment | a *= b | R & K :: operator *= ( Southward b ); | R & operator *= ( K & a , S b ); |
Partitioning assignment | a /= b | R & Yard :: operator /= ( S b ); | R & operator /= ( K & a , Southward b ); |
Modulo assignment | a %= b | R & Yard :: operator %= ( S b ); | R & operator %= ( K & a , S b ); |
Bitwise AND assignment | a &= b a and_eq b [b] | R & K :: operator &= ( S b ); | R & operator &= ( Chiliad & a , S b ); |
Bitwise OR consignment | a |= b a or_eq b [b] | R & Thou :: operator |= ( Due south b ); | R & operator |= ( K & a , S b ); |
Bitwise XOR consignment | a ^= b a xor_eq b [b] | R & Thousand :: operator ^= ( S b ); | R & operator ^= ( K & a , S b ); |
Bitwise left shift assignment | a <<= b | R & G :: operator <<= ( S b ); | R & operator <<= ( Thou & a , S b ); |
Bitwise right shift assignment[east] | a >>= b | R & K :: operator >>= ( Southward b ); | R & operator >>= ( Yard & a , Due south b ); |
Member and pointer operators [edit]
Operator proper name | Syntax | Can overload in C++ | Included in C | C++ paradigm examples | ||
---|---|---|---|---|---|---|
As member of K | Outside class definitions | |||||
Subscript | a[b] | Yeah | Yes | R & K :: operator []( Southward b ); | Due north/A | |
Indirection ("object pointed to by a") | *a | Aye | Yes | R & K :: operator * (); | R & operator * ( K a ); | |
Address-of ("address of a") | &a | Yes | Yep | R * Thousand :: operator & (); | R * operator & ( Thou a ); | |
Structure dereference ("member b of object pointed to by a") | a->b | Yes | Yep | R * K :: operator -> (); [f] | N/A | |
Structure reference ("member b of object a") | a.b | No | Yes | Due north/A | ||
Fellow member selected past pointer-to-member b of object pointed to by a [g] | a->*b | Yep | No | R & Thousand :: operator ->* ( Southward b ); | R & operator ->* ( K a , South b ); | |
Member of object a selected past arrow-to-fellow member b | a.*b | No | No | North/A |
Other operators [edit]
Operator name | Syntax | Can overload in C++ | Included in C | Image examples | ||
---|---|---|---|---|---|---|
As fellow member of K | Outside class definitions | |||||
Part call See Function object. | a(a1, a2) | Yes | Yes | R K::operator ()( Due south a , T b , ...); | N/A | |
Comma | a, b | Yep | Yep | R K :: operator ,( Southward b ); | R operator ,( Chiliad a , Southward b ); | |
Ternary conditional | a ? b : c | No | Yes | Due north/A | ||
Scope resolution | a::b | No | No | North/A | ||
User-defined literals[h] since C++11 | "a"_b | Yeah | No | N/A | R operator "" _b ( T a ) | |
Sizeof | sizeof(a) [i] sizeof(type) | No | Yep | North/A | ||
Size of parameter pack since C++eleven | sizeof...(Args) | No | No | N/A | ||
Alignof since C++11 | alignof(type) or _Alignof(blazon) [j] | No | Yes | N/A | ||
Blazon identification | typeid(a) typeid(type) | No | No | N/A | ||
Conversion (C-manner cast) | (type)a | Yes | Yep | G :: operator R (); [iii] | N/A | |
Conversion | blazon(a) | No | No | Note: behaves similar const_cast/static_cast/reinterpret_cast[4] | ||
static_cast conversion | static_cast<type>(a) | Yep | No | K :: operator R (); explicit K :: operator R (); since C++11 | Northward/A | |
Note: for user-defined conversions, the return type implicitly and necessarily matches the operator name. | ||||||
dynamic cast conversion | dynamic_cast<type>(a) | No | No | Northward/A | ||
const_cast conversion | const_cast<blazon>(a) | No | No | Northward/A | ||
reinterpret_cast conversion | reinterpret_cast<type>(a) | No | No | North/A | ||
Allocate storage | new type | Yes | No | void * K :: operator new ( size_t ten ); | void * operator new ( size_t x ); | |
Allocate storage (array) | new type [due north] | Aye | No | void * Thou :: operator new []( size_t a ); | void * operator new []( size_t a ); | |
Deallocate storage | delete a | Yes | No | void K :: operator delete ( void * a ); | void operator delete ( void * a ); | |
Deallocate storage (array) | delete[] a | Yes | No | void K :: operator delete []( void * a ); | void operator delete []( void * a ); | |
Exception cheque since C++11 | noexcept(a) | No | No | Due north/A |
Notes:
- ^ The modulus operator works just with integer operands, for floating signal numbers a library function must exist used instead (like
fmod
). - ^ a b c d due east f 1000 h i j k Requires
iso646.h
in C. See C++ operator synonyms - ^ About C++20 iii-way comparing
- ^ a b In the context of iostreams, writers often will refer to
<<
and>>
as the "put-to" or "stream insertion" and "get-from" or "stream extraction" operators, respectively. - ^ a b According to the C99 standard, the right shift of a negative number is implementation defined. About implementations, e.g., the GCC,[ii] employ an arithmetic shift (i.e., sign extension), only a logical shift is possible.
- ^ The return type of
operator -> ()
must be a blazon for which the->
operation tin can be applied, such as a pointer type. Ifx
is of typeC
whereC
overloadsoperator -> ()
,x -> y
gets expanded tox . operator -> () -> y
. - ^ Meyers, Scott (October 1999), "Implementing operator->* for Smart Pointers" (PDF), Dr. Dobb'south Periodical, Aristeia .
- ^ Well-nigh C++11 User-divers literals
- ^ The parentheses are not necessary when taking the size of a value, merely when taking the size of a type. However, they are ordinarily used regardless.
- ^ C++ defines
alignof
operator, whereas C defines_Alignof
. Both operators take the same semantics.
Operator precedence [edit]
The post-obit is a tabular array that lists the precedence and associativity of all the operators in the C and C++ languages. Operators are listed height 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 (there may be several rows of operators listed in a cell) are grouped with the same precedence, in the given direction. An operator'due south precedence is unaffected past overloading.
The syntax of expressions in C and C++ is specified by a phrase structure grammar.[5] The table given hither has been inferred from the grammer.[ citation needed ] For the ISO C 1999 standard, section 6.5.6 note 71 states that the C grammar provided past the specification defines the precedence of the C operators, and also states that the operator precedence resulting from the grammar closely follows the specification'southward department ordering:
"The [C] syntax [i.due east., grammer] specifies the precedence of operators in the evaluation of an expression, which is the same equally the order of the major subclauses of this subclause, highest precedence showtime."[half-dozen]
A precedence table, while mostly adequate, cannot resolve a few details. In particular, notation that the ternary operator allows any arbitrary expression as its middle operand, despite beingness listed every bit having higher precedence than the assignment and comma operators. Thus a ? b, c : d
is interpreted as a ? (b, c) : d
, and not as the meaningless (a ? b), (c : d)
. And then, the expression in the middle of the conditional operator (betwixt ?
and :
) is parsed as if parenthesized. Also, note that the firsthand, unparenthesized result of a C cast expression cannot be the operand of sizeof
. Therefore, sizeof (int) * x
is interpreted as (sizeof(int)) * x
and not sizeof ((int) * x)
.
Precedence | Operator | Description | Associativity |
---|---|---|---|
ane highest | :: | Telescopic resolution (C++ only) | None |
2 | ++ | Postfix increase | Left-to-correct |
-- | Postfix decrement | ||
() | Function call | ||
[] | Assortment subscripting | ||
. | Element selection by reference | ||
-> | Element selection through pointer | ||
typeid() | Run-time type information (C++ only) (run across typeid) | ||
const_cast | Blazon cast (C++ just) (see const_cast) | ||
dynamic_cast | Type cast (C++ simply) (see dynamic bandage) | ||
reinterpret_cast | Type cast (C++ just) (encounter reinterpret_cast) | ||
static_cast | Type cast (C++ only) (encounter static_cast) | ||
iii | ++ | Prefix increment | Correct-to-left |
-- | Prefix decrement | ||
+ | Unary plus | ||
- | Unary minus | ||
! | Logical Non | ||
~ | Bitwise Not (One's Complement) | ||
(type) | Type cast | ||
* | Indirection (dereference) | ||
& | Address-of | ||
sizeof | Sizeof | ||
_Alignof | Alignment requirement (since C11) | ||
new , new[] | Dynamic memory allotment (C++ merely) | ||
delete , delete[] | Dynamic retentivity deallocation (C++ only) | ||
4 | .* | Pointer to fellow member (C++ only) | Left-to-correct |
->* | Pointer to member (C++ simply) | ||
5 | * | Multiplication | Left-to-right |
/ | Division | ||
% | Modulo (residual) | ||
6 | + | Add-on | Left-to-right |
- | Subtraction | ||
7 | << | Bitwise left shift | Left-to-right |
>> | Bitwise correct shift | ||
8 | <=> | Three-way comparison (Introduced in C++20 - C++ but) | Left-to-right |
9 | < | Less than | Left-to-correct |
<= | Less than or equal to | ||
> | Greater than | ||
>= | Greater than or equal to | ||
x | == | Equal to | Left-to-right |
!= | Not equal to | ||
xi | & | Bitwise AND | Left-to-correct |
12 | ^ | Bitwise XOR (exclusive or) | Left-to-correct |
13 | | | Bitwise OR (inclusive or) | Left-to-right |
14 | && | Logical AND | Left-to-right |
15 | || | Logical OR | Left-to-right |
xvi | ?: | Ternary conditional (encounter ?:) | Correct-to-left |
= | Directly consignment | ||
+= | Assignment by sum | ||
-= | Consignment by difference | ||
*= | Assignment past product | ||
/= | Assignment by quotient | ||
%= | Assignment by remainder | ||
<<= | Assignment by bitwise left shift | ||
>>= | Assignment by bitwise right shift | ||
&= | Assignment by bitwise AND | ||
^= | Assignment by bitwise XOR | ||
|= | Assignment by bitwise OR | ||
throw | Throw operator (exceptions throwing, C++ only) | ||
17 lowest | , | Comma | Left-to-right |
[seven] [8] [9]
Notes [edit]
The precedence table determines the social club of binding in chained expressions, when it is not expressly specified by parentheses.
- For example,
++x*3
is ambiguous without some precedence rule(s). The precedence table tells us that: x is 'leap' more tightly to ++ than to *, then that whatever ++ does (now or later on—see below), it does it ONLY to x (and not tox*3
); it is equivalent to (++x
,x*3
). - Similarly, with
iii*x++
, where though the post-fix ++ is designed to act AFTER the entire expression is evaluated, the precedence tabular array makes it clear that ONLY x gets incremented (and Non3*ten
). In fact, the expression (tmp=ten++
,3*tmp
) is evaluated with tmp being a temporary value. Information technology is functionally equivalent to something similar (tmp=3*x
,++x
,tmp
).
- Abstracting the issue of precedence or bounden, consider the diagram higher up for the expression three+ii*y[i]++. The compiler'due south job is to resolve the diagram into an expression, one in which several unary operators (phone call them 3+( . ), 2*( . ), ( . )++ and ( . )[ i ]) are competing to bind to y. The order of precedence tabular array resolves the final sub-expression they each act upon: ( . )[ i ] acts merely on y, ( . )++ acts but on y[i], two*( . ) acts only on y[i]++ and 3+( . ) acts 'simply' on 2*((y[i])++). Information technology is important to annotation that WHAT sub-expression gets acted on by each operator is clear from the precedence tabular array simply WHEN each operator acts is non resolved by the precedence table; in this example, the ( . )++ operator acts only on y[i] by the precedence rules but binding levels alone do not signal the timing of the postfix ++ (the ( . )++ operator acts simply afterwards y[i] is evaluated in the expression).
Many of the operators containing multi-character sequences are given "names" built from the operator name of each character. For example, +=
and -=
are ofttimes called plus equal(s) and minus equal(s), instead of the more verbose "consignment by addition" and "assignment past subtraction". The binding of operators in C and C++ is specified (in the corresponding Standards) past a factored linguistic communication grammer, rather than a precedence table. This creates some subtle conflicts. For instance, in C, the syntax for a conditional expression is:
logical - OR - expression ? expression : conditional - expression
while in C++ it is:
logical - OR - expression ? expression : assignment - expression
Hence, the expression:
is parsed differently in the ii languages. In C, this expression is a syntax error, because the syntax for an assignment expression in C is:
unary - expression '=' assignment - expression
In C++, it is parsed as:
e = ( a < d ? a ++ : ( a = d ))
which is a valid expression.[10] [eleven]
If you want to utilize comma-as-operator within a unmarried function argument, variable consignment, or other comma-separated list, yous need to employ parentheses,[12] [13] e.g.:
int a = 1 , b = two , weirdVariable = ( ++ a , b ), d = 4 ;
Criticism of bitwise and equality operators precedence [edit]
The precedence of the bitwise logical operators has been criticized.[14] Conceptually, & and | are arithmetic operators similar * and +.
The expression a & b == vii
is syntactically parsed as a & ( b == 7 )
whereas the expression a + b == 7
is parsed as ( a + b ) == vii
. This requires parentheses to exist used more oft than they otherwise would.
Historically, in that location 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' (i.due east. when a Boolean value was expected, for example in if ( a == b & c ) {...}
it behaved as a logical operator, but in c = a & b
it behaved as a bitwise one). It was retained and then as to keep backward compatibility with existing installations.[fifteen]
Moreover, in C++ (and afterward versions of C) equality operations, with the exception of the 3-way comparison operator, yield bool type values which are conceptually a single bit (1 or 0) and as such do not properly belong in "bitwise" operations.
C++ operator synonyms [edit]
C++ defines[16] certain keywords to human action every bit aliases for a number of operators:
Keyword | Operator |
---|---|
and | && |
and_eq | &= |
bitand | & |
bitor | | |
compl | ~ |
not | ! |
not_eq | != |
or | || |
or_eq | |= |
xor | ^ |
xor_eq | ^= |
These tin exist 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 proper name (character string) of the respective operator. This means that the expressions (a > 0 and non flag)
and (a > 0 && !flag)
take identical meanings. It also means that, for case, the bitand
keyword may be used to replace not merely the bitwise-and operator just also the accost-of operator, and it tin fifty-fifty exist used to specify reference types (e.g., int bitand ref = north
). The ISO C specification makes allowance for these keywords every bit preprocessor macros in the header file iso646.h
. For compatibility with C, C++ provides the header ciso646
, the inclusion of which has no effect.
See also [edit]
- Bitwise operations in C
- Bit manipulation
- Logical operator
- Boolean algebra (logic)
- Table of logic symbols
- Digraphs and trigraphs in C and in C++
References [edit]
- ^ "Standard C++".
- ^ "Integers implementation", GCC 4.iii.3, GNU .
- ^ "user-divers conversion". Retrieved five April 2020.
- ^ Explicit type conversion in C++
- ^ ISO/IEC 9899:201x Programming Languages - C. open up-std.org – The C Standards Committee. 19 December 2011. p. 465.
- ^ the ISO C 1999 standard, section vi.5.6 note 71 (Technical report). ISO. 1999.
- ^ "C Operator Precedence - cppreference.com". en.cppreference.com . Retrieved 16 July 2019.
- ^ "C++ Congenital-in Operators, Precedence and Associativity". docs.microsoft.com . Retrieved eleven May 2020.
- ^ "C++ Operator Precedence - cppreference.com". en.cppreference.com . Retrieved 16 July 2019.
- ^ "C Operator Precedence - cppreference.com". en.cppreference.com . Retrieved 10 April 2020.
- ^ "Does the C/C++ ternary operator actually have the same precedence as consignment operators?". Stack Overflow . Retrieved 22 September 2019.
- ^ "Other operators - cppreference.com". en.cppreference.com . Retrieved 10 April 2020.
- ^ "c++ - How does the Comma Operator work". Stack Overflow . Retrieved i April 2020.
- ^ C history § Neonatal C, Bell labs .
- ^ "Re^x: adjacent unless status". world wide web.perlmonks.org . Retrieved 23 March 2018.
- ^ ISO/IEC 14882:1998(E) Programming Language C++. open up-std.org – The C++ Standards Committee. ane September 1998. pp. 40–41.
External links [edit]
- "Operators", C++ reference (wiki) .
- C Operator Precedence
- Postfix Increment and Decrement Operators: ++ and -- (Developer network), Microsoft .
Source: https://en.wikipedia.org/wiki/Operators_in_C_and_C%2B%2B
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