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An expression is a special kind of statement that evaluates to a value. Every expression is composed of −
-
Operands − Represents the data
-
Operator − Defines how the operands will be processed to produce a value.
Consider the following expression – “2 + 3”. In this expression, 2 and 3 are operands and the symbol “+” (plus) is the operator.
In this chapter, we will discuss the operators that are available in Dart.
- Arithmetic Operators
- Equality and Relational Operators
- Type test Operators
- Bitwise Operators
- Assignment Operators
- Logical Operators
Arithmetic Operators
The following table shows the arithmetic operators supported by Dart.
| Sr.No | Operators & Meaning |
|---|---|
| 1 | +
Add |
| 2 | −
Subtract |
| 3 | -expr
Unary minus, also known as negation (reverse the sign of the expression) |
| 4 | *
Multiply |
| 5 | /
Divide |
| 6 | ~/
Divide, returning an integer result |
| 7 | %
Get the remainder of an integer division (modulo) |
| 8 | ++
Increment |
| 9 | —
Decrement |
Equality and Relational Operators
Relational Operators tests or defines the kind of relationship between two entities. Relational operators return a Boolean value i.e. true/ false.
Assume the value of A is 10 and B is 20.
| Operator | Description | Example |
|---|---|---|
| > | Greater than | (A > B) is False |
| < | Lesser than | (A < B) is True |
| >= | Greater than or equal to | (A >= B) is False |
| <= | Lesser than or equal to | (A <= B) is True |
| == | Equality | (A==B) is False |
| != | Not equal | (A!=B) is True |
Type test Operators
These operators are handy for checking types at runtime.
| Operator | Meaning |
|---|---|
| is | True if the object has the specified type |
| is! | False if the object has the specified type |
Bitwise Operators
The following table lists the bitwise operators available in Dart and their role −
| Operator | Description | Example |
|---|---|---|
| Bitwise AND | a & b | Returns a one in each bit position for which the corresponding bits of both operands are ones. |
| Bitwise OR | a | b | Returns a one in each bit position for which the corresponding bits of either or both operands are ones. |
| Bitwise XOR | a ^ b | Returns a one in each bit position for which the corresponding bits of either but not both operands are ones. |
| Bitwise NOT | ~ a | Inverts the bits of its operand. |
| Left shift | a ≪ b | Shifts a in binary representation b (< 32) bits to the left, shifting in zeroes from the right. |
| Signpropagating right shift | a ≫ b | Shifts a in binary representation b (< 32) bits to the right, discarding bits shifted off. |
Assignment Operators
The following table lists the assignment operators available in Dart.
| Sr.No | Operator & Description |
|---|---|
| 1 | =(Simple Assignment )
Assigns values from the right side operand to the left side operand Ex:C = A + B will assign the value of A + B into C |
| 2 | ??=
Assign the value only if the variable is null |
| 3 | +=(Add and Assignment)
It adds the right operand to the left operand and assigns the result to the left operand. Ex: C += A is equivalent to C = C + A |
| 4 | ─=(Subtract and Assignment)
It subtracts the right operand from the left operand and assigns the result to the left operand. Ex: C -= A is equivalent to C = C – A |
| 5 | *=(Multiply and Assignment)
It multiplies the right operand with the left operand and assigns the result to the left operand. Ex: C *= A is equivalent to C = C * A |
| 6 | /=(Divide and Assignment)
It divides the left operand with the right operand and assigns the result to the left operand. |
Note − Same logic applies to Bitwise operators, so they will become ≪=, ≫=, ≫=, ≫=, |= and ^=.
Logical Operators
Logical operators are used to combine two or more conditions. Logical operators return a Boolean value. Assume the value of variable A is 10 and B is 20.
| Operator | Description | Example |
|---|---|---|
| && |
And − The operator returns true only if all the expressions specified return true |
(A > 10 && B > 10) is False. |
| || |
OR − The operator returns true if at least one of the expressions specified return true |
(A > 10 || B > 10) is True. |
| ! |
NOT − The operator returns the inverse of the expression’s result. For E.g.: !(7>5) returns false |
!(A > 10) is True. |
Conditional Expressions
Dart has two operators that let you evaluate expressions that might otherwise require ifelse statements −
condition ? expr1 : expr2
If condition is true, then the expression evaluates expr1 (and returns its value); otherwise, it evaluates and returns the value of expr2.
expr1 ?? expr2
If expr1 is non-null, returns its value; otherwise, evaluates and returns the value of expr2
Example
The following example shows how you can use conditional expression in Dart −
void main() {
var a = 10;
var res = a > 12 ? "value greater than 10":"value lesser than or equal to 10";
print(res);
}
It will produce the following output −
value lesser than or equal to 10
Example
Let’s take another example −
void main() {
var a = null;
var b = 12;
var res = a ?? b;
print(res);
}
It will produce the following output −
12
”;