# D Programming - Operators

An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations. D language 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 chapter explains arithmetic, relational, logical, bitwise, assignment, and other operators one by one.

## Arithmetic Operators

The following table shows all arithmetic operators supported by D language. Assume variable **A** holds 10 and variable **B** holds 20 then −

Operator | Description | Example |
---|---|---|

+ | It adds two operands. | A + B gives 30 |

- | It subtracts second operand from the first. | A - B gives -10 |

* | It multiplies both operands. | A * B gives 200 |

/ | It divides numerator by denumerator. | B / A gives 2 |

% | It returns remainder of an integer division. | B % A gives 0 |

++ | The increment operator increases integer value by one. | A++ gives 11 |

-- | The decrements operator decreases integer value by one. | A-- gives 9 |

## Relational Operators

The following table shows all the relational operators supported by D language. Assume variable **A** holds 10 and variable **B** holds 20, then −

Operator | Description | Example |
---|---|---|

== | Checks if the values of two operands are equal or not, if yes then condition becomes true. | (A == B) is not true. |

!= | Checks if the values of two operands are equal or not, if values are not equal then condition becomes true. | (A != B) is true. |

> | Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true. | (A > B) is not true. |

< | Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true. | (A < B) is true. |

>= | Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true. | (A >= B) is not true. |

<= | Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true. | (A <= B) is true. |

## Logical Operators

The following table shows all the logical operators supported by D language. Assume variable **A** holds 1 and variable **B** holds 0, then −

Operator | Description | Example |
---|---|---|

&& | It is called Logical AND operator. If both the operands are non-zero, then condition becomes true. | (A && B) is false. |

|| | It is called Logical OR Operator. If any of the two operands is non-zero, then condition becomes true. | (A || B) is true. |

! | It is called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false. | !(A && B) is true. |

## Bitwise Operators

Bitwise operators 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 | 1 | 1 | 1 | 0 |

1 | 0 | 0 | 1 | 1 |

Assume if A = 60; and B = 13. In the binary format they will be as follows −

A = 0011 1100

B = 0000 1101

-----------------

A&B = 0000 1100

A|B = 0011 1101

A^B = 0011 0001

~A = 1100 0011

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

Operator | Description | Example |
---|---|---|

& | Binary AND Operator copies a bit to the result if it exists in both operands. | (A & B) will give 12, Means 0000 1100. |

| | Binary OR Operator copies a bit if it exists in either operand. | (A | B) gives 61. Means 0011 1101. |

^ | Binary XOR Operator copies the bit if it is set in one operand but not both. | (A ^ B) gives 49. Means 0011 0001 |

~ | Binary Ones Complement Operator is unary and has the effect of 'flipping' bits. | (~A ) gives -61. Means 1100 0011 in 2's complement form. |

<< | Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand. | A << 2 give 240. Means 1111 0000 |

>> | Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand. | A >> 2 give 15. Means 0000 1111. |

## Assignment Operators

The following assignment operators are supported by D language −

Operator | Description | Example |
---|---|---|

= | It is simple assignment operator. It assigns values from right side operands to left side operand | C = A + B assigns value of A + B into C |

+= | It is 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 |

-= | It is 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 |

*= | It is multiply AND assignment operator. It multiplies right operand with the left operand and assigns the result to left operand. | C *= A is equivalent to C = C * A |

/= | It is 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 |

%= | It is 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 |

<<= | It is Left shift AND assignment operator. | C <<= 2 is same as C = C << 2 |

>>= | It is Right shift AND assignment operator. | C >>= 2 is same as C = C >> 2 |

&= | It is bitwise AND assignment operator. | C &= 2 is same as C = C & 2 |

^= | It is bitwise exclusive OR and assignment operator. | C ^= 2 is same as C = C ^ 2 |

|= | It is bitwise inclusive OR and assignment operator | C |= 2 is same as C = C | 2 |

## Miscillaneous Operators − Sizeof and Ternary

There are few other important operators including **sizeof** and **? :** supported by D Language.

Operator | Description | Example |
---|---|---|

sizeof() | Returns the size of an variable. | sizeof(a), where a is integer, returns 4. |

& | Returns the address of a variable. | &a; gives actual address of the variable. |

* | Pointer to a variable. | *a; gives pointer to a variable. |

? : | Conditional Expression | If condition is true then value X: Otherwise value Y. |

## Operators Precedence in D

Operator precedence determines the grouping of terms in an expression. This affects how an expression is evaluated. Certain operators are given precedence over others.

For example, the multiplication operator has higher precedence than the addition operator.

Let us consider an expression

x = 7 + 3 * 2.

Here, x is assigned 13, not 20. The simple reason is, the operator * has higher precedence than +, hence 3*2 is calculated first and then the result is added 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 are 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 |