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Dart Programming - Operators

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Dart Programming - Operators



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.

Show Examples

Sr.NoOperators & 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.

Show Examples

OperatorDescriptionExample
>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.

Show Examples

OperatorMeaning
isTrue 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 −

Show Examples

OperatorDescriptionExample
Bitwise ANDa & bReturns a one in each bit position for which the corresponding bits of both operands are ones.
Bitwise ORa | bReturns a one in each bit position for which the corresponding bits of either or both operands are ones.
Bitwise XORa ^ bReturns a one in each bit position for which the corresponding bits of either but not both operands are ones.
Bitwise NOT~ aInverts the bits of its operand.
Left shifta ≪ bShifts a in binary representation b (< 32) bits to the left, shifting in zeroes from the right.
Signpropagating right shifta ≫ bShifts 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.

Show Examples

Sr.NoOperator & 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.

Show Examples

OperatorDescriptionExample
&&

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 −

 Live Demo
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

Dart Programming - Loops

At times, certain instructions require repeated execution. Loops are an ideal way to do the same. A loop represents a set of instructions that must be repeated. In a loop’s context, a repetition is termed as an iteration.

The following figure illustrates the classification of loops −

Classification Of Loops

Let’s start the discussion with Definite Loops. A loop whose number of iterations are definite/fixed is termed as a definite loop.

Sr.NoLoop & Description
1for loop

The for loop is an implementation of a definite loop. The for loop executes the code block for a specified number of times. It can be used to iterate over a fixed set of values, such as an array

2for…in Loop

The for...in loop is used to loop through an object's properties.

Moving on, let’s now discuss the indefinite loops. An indefinite loop is used when the number of iterations in a loop is indeterminate or unknown. Indefinite loops can be implemented using −

Sr.NoLoop & Description
1while Loop

The while loop executes the instructions each time the condition specified evaluates to true. In other words, the loop evaluates the condition before the block of code is executed.

2do…while Loop

The do…while loop is similar to the while loop except that the do...while loop doesn’t evaluate the condition for the first time the loop executes.

Let us now move on and discuss the Loop Control Statements of Dart.

Sr.NoControl Statement & Description
1break Statement

The break statement is used to take the control out of a construct. Using break in a loop causes the program to exit the loop. Following is an example of the break statement.

2continue Statement

The continue statement skips the subsequent statements in the current iteration and takes the control back to the beginning of the loop.

Using Labels to Control the Flow

A label is simply an identifier followed by a colon (:) that is applied to a statement or a block of code. A label can be used with break and continue to control the flow more precisely.

Line breaks are not allowed between the ‘continue’ or ‘break’ statement and its label name. Also, there should not be any other statement in between a label name and an associated loop.

Example: Label with Break

 Live Demo
void main() { 
   outerloop: // This is the label name 
   
   for (var i = 0; i < 5; i++) { 
      print("Innerloop: ${i}"); 
      innerloop: 
      
      for (var j = 0; j < 5; j++) { 
         if (j > 3 ) break ; 
         
         // Quit the innermost loop 
         if (i == 2) break innerloop; 
         
         // Do the same thing 
         if (i == 4) break outerloop; 
         
         // Quit the outer loop 
         print("Innerloop: ${j}"); 
      } 
   } 
}

The following output is displayed on successful execution of the above code.

Innerloop: 0
Innerloop: 0
Innerloop: 1
Innerloop: 2
Innerloop: 3
Innerloop: 1
Innerloop: 0
Innerloop: 1
Innerloop: 2
Innerloop: 3
Innerloop: 2
Innerloop: 3
Innerloop: 0
Innerloop: 1
Innerloop: 2
Innerloop: 3
Innerloop: 4

Example: Label with continue

 Live Demo
void main() { 
   outerloop: // This is the label name 
   
   for (var i = 0; i < 3; i++) { 
      print("Outerloop:${i}"); 
      
      for (var j = 0; j < 5; j++) { 
         if (j == 3){ 
            continue outerloop; 
         } 
         print("Innerloop:${j}"); 
      } 
   } 
}

The following output is displayed on successful execution of the above code.

Outerloop: 0 
Innerloop: 0 
Innerloop: 1 
Innerloop: 2 

Outerloop: 1 
Innerloop: 0 
Innerloop: 1 
Innerloop: 2 

Outerloop: 2 
Innerloop: 0 
Innerloop: 1 
Innerloop: 2

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