C++ Operators

# Introduction

An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations. C++ is rich in built-in operators and provides the following types of operators:

• Arithmetic operators
• Relational operators
• Logical operators
• Bitwise operators
• Assignment operators
• Misc operators

This page will examine the arithmetic, relational, logical, bitwise, assignment and other operators one by one.

## Arithmetic operators

There are following arithmetic operators supported by C++:

Assume variable A holds 15 and variable B holds 30, then:

Operator Description Example
+ Adds two operands A + B will give 45
- Subtracts second operand from the first B - A will give 15
* Multiplies both operands A*B will give 450
/ Divides numerator by de-numerator B/A will give 2
% Modulus Operator and remainder of after an integer division A % B will give 15 and B % A will give 0
++ Increment operator, increases integer value by one ++A will increment A and give 16, while A++ will give 15 and then increment A
-- Decrement operator, decreases integer value by one --B will decrement B and give 29, while B-- will give 30 and then decrement B

## Relational operators

There are following relational operators supported by C++:

Assume variable A holds 15 and variable B holds 30, then:

Operator Description Example
== Checks whether the values of the two operands are equal or not (A == B) is false
!= Checks whether the values of the two operands are different or not (A != B) is true
> Checks whether the value of the first operand is greater than the second (A > B) is false
>= Checks whether the value of the first operand is greater than or equal to the second (A >= B) is false
< Checks whether the value of the first operand is less than the second (A < B) is true
<= Checks whether the value of the first operand is less than or equal to the second (A <= B) is true

[[/table]]

## Logical operators

There are following logical operators supported by C++:

Assume variable A holds 0 and variable B holds 1, then:

Operator Description Example
&& Called Logical AND. If both of the operands are non-zero, then condition becomes true. (A && B) is false
|| Called Logical OR. If either of the operands is non-zero, then condition becomes true. (A || B) is true
! Called Logical NOT. It reverses the logical state from true to false and vice-versa. !(A && B) is true

## Bitwise operators

Bitwise operator works on bits and perform bit-by-bit operation. The truth tables for &, |, and ^ are as follows:

p q p & q p | q p ^ q
0 0 0 0 0
0 1 0 1 1
1 0 0 1 1
1 1 1 1 0

The Bitwise operators supported by C++ language are listed in the following table. Assume variable A holds 60 and variable B holds 13, then:

Operator Description Example
& Binary AND copies a bit to the result if it exists in both operands. (A & B) will give 12 which is 0000 1100
| Binary OR copies a bit if it exists in either operand. (A | B) will give 61 which is 0011 1101
^ Binary XOR copies the bit if it is set in one operand but not both. (A ^ B) will give 49 which is 0011 0001
~ Binary Ones Complement is unary and has the effect of 'flipping' bits. (~A ) will give -61 which is 1100 0011 in 2's complement form due to a signed binary number.
<< Binary Left Shift. The left operands value is moved left by the number of bits specified by the right operand. A << 2 will give 240 which is 1111 0000
>> Binary Right Shift. The left operands value is moved right by the number of bits specified by the right operand. A >> 2 will give 15 which is 0000 1111

## Assignment operators

There are following assignment operators supported by C++ language:

Operator Description Example
= Simple assignment operator, Assigns values from right side operands to left side operand C = A + B will assign value of A + B into C
+= Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand C += A is equivalent to C = C + A
-= Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to left operand C -= A is equivalent to C = C - A
*= Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand C *= A is equivalent to C = C * A
/= Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand C /= A is equivalent to C = C / A
%= Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand C %= A is equivalent to C = C % A
<<= Left shift AND assignment operator C <<= 2 is same as C = C << 2
>>= Right shift AND assignment operator C >>= 2 is same as C = C >> 2
&= Bitwise AND assignment operator C &= 2 is same as C = C & 2
^= Bitwise exclusive OR and assignment operator C ^= 2 is same as C = C ^ 2
|= Bitwise inclusive OR and assignment operator C |= 2 is same as C = C | 2

## Misc operators

There are few other operators supported by C++ Language.

Operator Description
sizeof sizeof operator returns the size of a variable. For example, sizeof(a), where a is integer, will return 4.
Condition ? X : Y Conditional operator. If Condition is true ? then it returns value X : otherwise value Y
, Comma operator causes a sequence of operations to be performed. The value of the entire comma expression is the value of the last expression of the comma-separated list.
. (dot) and -> (arrow) Member operators are used to reference individual members of classes, structures, and unions.
Cast Casting operators convert one data type to another. For example, int(2.2000) would return 2.
& Pointer operator & returns the address of an variable. For example &a; will give actual address of the variable.
* Pointer operator * dereferences a pointer. For example *var; will give the value pointed to by var.

# Operator precedence in C++

Operator precedence determines the grouping of terms in an expression. This affects how an expression is evaluated. Certain operators have higher precedence than others; for example, the multiplication operator has higher precedence than the addition operator:

For example x = 7 + 3 * 2; here, x is assigned 13, not 20 because operator * has higher precedence than +, so it first gets multiplied with 3*2 and then adds into 7.

Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom. Within an expression, higher precedence operators will be evaluated first.

Category Operator Associativity
Postfix () [] -> . ++ - - Left to right
Unary + - ! ~ ++ - - (type)* & sizeof Right to left
Multiplicative * / % Left to right
Additive + - Left to right
Shift << >> Left to right
Relational < <= > >= Left to right
Equality == != Left to right
Bitwise AND & Left to right
Bitwise XOR ^ Left to right
Bitwise OR | Left to right
Logical AND && Left to right
Logical OR || Left to right
Conditional ?: Right to left
Assignment = += -= *= /= %=>>= <<= &= ^= |= Right to left
Comma , Left to right
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