This is a list ofoperators in theC andC++programming languages.

All listed operators are in C++ and lacking indication otherwise, in C as well. Some tables include a "In C" column that indicates whether an operator is also in C. Note that C does not supportoperator overloading.

When not overloaded, for the operators&&,||, and, (thecomma operator), there is asequence point after the evaluation of the first operand.

Most of the operators available in C and C++ are also available in otherC-family languages such asC#,D,Java,Perl, andPHP with the same precedence, associativity, and semantics.

Many operators specified by a sequence of symbols are commonly referred to by a name that consists of the name of each symbol. For example,+= and-= are often called "plus equal(s)" and "minus equal(s)", instead of the more verbose "assignment by addition" and "assignment by subtraction".

In the following tables, lower case letters such asa andb represent literal values, object/variable names, or l-values, as appropriate.R,S andT stand for a data type, andK for a class or enumeration type. Some operators have alternative spellings usingdigraphs and trigraphs oroperator synonyms.

C and C++ have the same arithmetic operators and all can be overloaded in C++.

Allrelational (comparison) operators can be overloaded in C++. SinceC++20, the inequality operator is automatically generated ifoperator== is defined and all four relational operators are automatically generated ifoperator<=> is defined.^[1]

C and C++ have the same logical operators and all can be overloaded in C++.

Note that overloading logicalAND andOR is discouraged, because as overloaded operators they always evaluate both operands instead of providing the normal semantics ofshort-circuit evaluation.^[2]

C and C++ have the same bitwise operators and all can be overloaded in C++.

C and C++ have the same assignment operators and all can be overloaded in C++.

For the combination operators,a ⊚= b (where⊚ represents an operation) is equivalent toa = a ⊚ b, except thata is evaluated only once.

C++ defines keywords to act as aliases for a number of operators:^[7]

Each keyword is a different way to specify an operator and as such can be used instead of the corresponding symbolic variation. For example,(a > 0 and not flag) and(a > 0 && !flag) specify the same behavior. As another example, thebitand keyword may be used to replace not only thebitwise-and operator but also theaddress-of operator, and it can be used to specify reference types (e.g.,int bitand ref = n).

The ISO C specification makes allowance for these keywords as preprocessor macros in the header fileiso646.h. For compatibility with C, C++ also provides the headeriso646.h, the inclusion of which has no effect. Until C++20, it also provided the corresponding headerciso646 which had no effect as well.

During expression evaluation, the order in which sub-expressions are evaluated is determined byprecedence andassociativity. An operator with higher precedence is evaluated before a operator of lower precedence and the operands of an operator are evaluated based on associativity. The following table describes the precedence and associativity of the C and C++ operators. Operators are shown in groups of equal precedence with groups ordered in descending precedence from top to bottom (lower order is higher precedence).^[8][9][10]

Operator precedence is not affected by overloading.

Although this table is adequate for describing most evaluation order, it does not describe a few details. Theternary operator allows any arbitrary expression as its middle operand, despite being listed as having higher precedence than the assignment and comma operators. Thusa ? b, c : d is interpreted asa ? (b, c) : d, and not as the meaningless(a ? b), (c : d). So, the expression in the middle of the conditional operator (between? and:) is parsed as if parenthesized. Also, the immediate, un-parenthesized result of a C cast expression cannot be the operand ofsizeof. Therefore,sizeof (int) * x is interpreted as(sizeof(int)) * x and notsizeof ((int) * x).

The precedence table determines the order 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 'bound' more tightly to++ than to*, so that whatever++ does (now or later—see below), it does it ONLY tox (and not tox*3); it is equivalent to (++x,x*3).
• Similarly, with3*x++, where though the post-fix++ is designed to act AFTER the entire expression is evaluated, the precedence table makes it clear that ONLYx gets incremented (and NOT3*x). In fact, the expression (tmp=x++,3*tmp) is evaluated withtmp being a temporary value. It is functionally equivalent to something like (tmp=3*x,++x,tmp).

• Abstracting the issue of precedence or binding, consider the diagram above for the expression 3+2*y[i]++. The compiler's job is to resolve the diagram into an expression, one in which several unary operators (call them 3+( . ), 2*( . ), ( . )++ and ( . )[ i ]) are competing to bind to y. The order of precedence table resolves the final sub-expression they each act upon: ( . )[ i ] acts only on y, ( . )++ acts only on y[i], 2*( . ) acts only on y[i]++ and 3+( . ) acts 'only' on 2*((y[i])++). It is important to note that WHAT sub-expression gets acted on by each operator is clear from the precedence table but WHEN each operator acts is not 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 indicate the timing of the postfix ++ (the ( . )++ operator acts only after y[i] is evaluated in the expression).

The binding of operators in C and C++ is specified by a factored language grammar, rather than a precedence table. This creates some subtle conflicts. For example, 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:

e = a < d ? a++ : a = d

is parsed differently in the two 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.^[11][12]

To use the comma operator in a function call argument expression, variable assignment, or a comma-separated list, use of parentheses is required.^[13][14] For example,

inta=1,b=2,weirdVariable=(++a,b),d=4;

The precedence of the bitwise logical operators has been criticized.^[15] Conceptually, & and | are arithmetic operators like * and +.

The expressiona&b==7 is syntactically parsed asa&(b==7) whereas the expressiona+b==7 is parsed as(a+b)==7. This requires parentheses to be used more often than they otherwise would.

Historically, there was no syntactic distinction between the bitwise and logical operators. InBCPL,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.e. when a Boolean value was expected, for example inif(a==b&c){...} it behaved as a logical operator, but inc=a&b it behaved as a bitwise one). It was retained so as to keepbackward compatibility with existing installations.^[16]

Moreover, in C++ (and later versions of C) equality operations, with the exception of the three-way comparison operator, yieldbool type values which are conceptually a single bit (1 or 0) and as such do not properly belong in "bitwise" operations.

• Bitwise operations in C – Operations transforming individual bits of integral data types
• Bit manipulation – Algorithmically modifying data below the word level
• Logical operator – Symbol connecting formulas in logicPages displaying short descriptions of redirect targets
• Boolean algebra (logic) – Algebraic manipulation of "true" and "false"Pages displaying short descriptions of redirect targets
• Table of logic symbols – List of symbols used to express logical relationsPages displaying short descriptions of redirect targets

• "Operators",C++ reference (wiki).
• C Operator Precedence
• Postfix Increment and Decrement Operators: ++ and -- (Developer network), Microsoft, 17 August 2021.

• C (programming language)
• C++
• Operators (programming)
• Comparison of individual programming languages

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