Dart Operators and Dart expressions

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Dart Operators and Expressions: A Comprehensive Guide to Dart Programming”

Introduction:
Explore the fundamental concepts of Dart operators and expressions with our comprehensive guide. Learn how to perform arithmetic operations, make logical decisions, and leverage assignment operators in Dart programming. This lesson provides hands-on examples and explanations to enhance your understanding of Dart’s powerful features.

In Dart, operators are symbols that represent computations, manipulations, or logical operations on variables and values. Expressions, on the other hand, are combinations of literals, variables, operators, and function invocations that can be evaluated to produce a value.

Here are some of Dart operators and expressions:

Arithmetic Operators:

+ (addition)
– (subtraction)
* (multiplication)
/ (division)
% (modulo, returns the remainder of division)

Example:

dart

int a = 10;
int b = 3;

print(a + b); // 13
print(a - b); // 7
print(a * b); // 30
print(a / b); // 3.3333
print(a % b); // 1

Relational Operators:

== (equality)
!= (not equal)
> (greater than)
< (less than)
>= (greater than or equal to)
<= (less than or equal to)

Example:

dart

int x = 5;
int y = 10;

print(x == y); // false
print(x != y); // true
print(x > y); // false
print(x < y); // true
print(x >= y); // false
print(x <= y); // true
Logical Operators:
&& (logical AND)
|| (logical OR)
! (logical NOT)

Example:

dart

bool isTrue = true;
bool isFalse = false;

print(isTrue && isFalse); // false
print(isTrue || isFalse); // true
print(!isTrue); // false

Assignment Operators:

= (assignment)
+= (add and assign)
-= (subtract and assign)
*= (multiply and assign)
/= (divide and assign)
Example:

dart

int num = 10;

num += 5; // num is now 15
num -= 3; // num is now 12
num *= 2; // num is now 24
num /= 4; // num is now 6

Conditional Operator (Ternary):

dart

int a = 5;
int b = 10;

int result = (a > b) ? a : b;
print(result); // 10

These are some of the basic operators in Dart. Understanding how to use them in expressions is essential for writing effective and concise Dart code.

complete example with explanation

Let’s create a complete Dart example that utilizes various operators and expressions to perform calculations and make logical decisions.

dart

void main() {
// Arithmetic Operators
int a = 10;
int b = 3;

int sum = a + b; // Addition
int difference = a - b; // Subtraction
int product = a * b; // Multiplication
double quotient = a / b; // Division
int remainder = a % b; // Modulo

print("Arithmetic Operators:");
print("Sum: $sum");
print("Difference: $difference");
print("Product: $product");
print("Quotient: $quotient");
print("Remainder: $remainder");
print("\n");

// Relational Operators
int x = 5;
int y = 10;

bool isEqual = x == y;
bool isNotEqual = x != y;
bool isGreaterThan = x > y;
bool isLessThan = x < y;
bool isGreaterOrEqual = x >= y;
bool isLessOrEqual = x <= y;

print("Relational Operators:");
print("Equal: $isEqual");
print("Not Equal: $isNotEqual");
print("Greater Than: $isGreaterThan");
print("Less Than: $isLessThan");
print("Greater or Equal: $isGreaterOrEqual");
print("Less or Equal: $isLessOrEqual");
print("\n");

// Logical Operators
bool isTrue = true;
bool isFalse = false;

bool logicalAnd = isTrue && isFalse;
bool logicalOr = isTrue || isFalse;
bool logicalNot = !isTrue;

print("Logical Operators:");
print("Logical AND: $logicalAnd");
print("Logical OR: $logicalOr");
print("Logical NOT: $logicalNot");
print("\n");

// Assignment Operators
int num = 10;

num += 5; // Add and assign
num -= 3; // Subtract and assign
num *= 2; // Multiply and assign
num /= 4; // Divide and assign

print("Assignment Operators:");
print("Final Value: $num");
print("\n");

// Conditional Operator (Ternary)
int valueA = 5;
int valueB = 10;

int result = (valueA > valueB) ? valueA : valueB;
print("Conditional Operator (Ternary):");
print("Result: $result");
}

Explanation:

The example begins by demonstrating arithmetic operations, relational comparisons, logical operations, and assignment operations.
It prints the results at each step, showing how the values change through different operations.
The last part demonstrates the conditional (ternary) operator, making a decision based on a condition.
You can run this Dart code to see the output and understand how these operators and expressions work together.

The out put of this example

If you run the provided Dart example, the output should be as follows:

Arithmetic Operators:
Sum: 13
Difference: 7
Product: 30
Quotient: 3.3333333333333335
Remainder: 1

Relational Operators:
Equal: false
Not Equal: true
Greater Than: false
Less Than: true
Greater or Equal: false
Less or Equal: true

Logical Operators:
Logical AND: false
Logical OR: true
Logical NOT: false

Assignment Operators:
Final Value: 6

Conditional Operator (Ternary):
Result: 10

This output reflects the results of the various arithmetic, relational, logical, and assignment operations in the Dart example. The values are computed and printed at each step of the code.

An application about this lesson 

Let’s create a simple Dart console application that incorporates the concepts of operators and expressions. In this example, we’ll create a calculator application that performs basic arithmetic operations based on input.

dart

import 'dart:io';

void main() {
print("Welcome to the Simple Calculator!");

// Get input for two numbers
double num1 = getNumber("Enter the first number: ");
double num2 = getNumber("Enter the second number: ");

// Perform arithmetic operations
double sum = num1 + num2;
double difference = num1 - num2;
double product = num1 * num2;
double quotient = num1 / num2;

// Display results
print("\nArithmetic Results:");
print("Sum: $sum");
print("Difference: $difference");
print("Product: $product");
print("Quotient: $quotient");

// Get input for a logical operation
bool isTrue = getBoolean("Enter true or false: ");
bool isFalse = !isTrue;

// Perform logical operations
bool logicalAnd = isTrue && isFalse;
bool logicalOr = isTrue || isFalse;

// Display logical results
print("\nLogical Results:");
print("Logical AND: $logicalAnd");
print("Logical OR: $logicalOr");
}

// Helper function to get a valid number from the
double getNumber(String prompt) {
double number;
while (true) {
try {
stdout.write(prompt);
String input = stdin.readLineSync()!;
number = double.parse(input);
break;
} catch (e) {
print("Invalid input. Please enter a valid number.");
}
}
return number;
}

// Helper function to get a valid boolean from the
bool getBoolean(String prompt) {
bool value;
while (true) {
stdout.write(prompt);
String input = stdin.readLineSync()!.toLowerCase();
if (input == 'true' || input == 'false') {
value = input == 'true';
break;
} else {
print("Invalid input. Please enter 'true' or 'false'.");
}
}
return value;
}

Explanation:

The application starts by welcoming the to the Simple Calculator.
It then prompts the to enter two numbers for arithmetic operations and performs addition, subtraction, multiplication, and division.
The application also prompts the to enter a boolean value and performs logical AND and OR operations.
Helper functions getNumber and getBoolean are used to ensure that the input is valid.
The results of the calculations are displayed to the .
To run this Dart application, save it in a Dart file (e.g., calculator.dart) and execute it using the Dart SDK:

dart calculator.dart
Follow the prompts to enter numbers and boolean values, and the application will display the results based on the provided input.

Quiz about this lesson :15 questions 

Here’s a quiz with 15 questions about Dart operators and expressions. Each question is followed by an explanation of the correct answer.

Quiz:
1-What does the % operator do in Dart?

a. Addition
b. Modulo
c. Multiplication
d. Division

2-Which operator is used for logical AND in Dart?

a. &
b. &&
c. ||
d. !

3-What is the result of the expression 10 / 3 in Dart?

a. 3
b. 3.33
c. 3.0
d. 4

4-What is the purpose of the != operator in Dart?

a. Greater than or equal to
b. Not equal to
c. Less than or equal to
d. Equal to

5-Which operator is used for assignment in Dart?

a. =
b. ==
c. +=
d. /=

6-What does the ! operator do in Dart?

a. Logical AND
b. Logical OR
c. Logical NOT
d. Modulo

7-In Dart, what does the >= operator represent?

a. Greater than or equal to
b. Less than or equal to
c. Greater than
d. Less than

8-Which operator is used for logical OR in Dart?

a. ||
b. &
c. !
d. &&

9-What is the value of num after the operation num *= 3 if num is initially 5?

a. 15
b. 8
c. 18
d. 5

10-What is the result of the expression (true && false) || true in Dart?

a. true
b. false
c. true && false
d. true || false

11-Which operator is used for equality comparison in Dart?

a. =
b. !=
c. ==
d. >=

12-What does the ?? operator do in Dart?

a. Conditional (Ternary)
b. Null-aware coalescing
c. Logical AND
d. Logical OR

13-What is the result of the expression 5 ~/ 2 in Dart?

a. 2.5
b. 2
c. 3
d. 2.0

14-What is the purpose of the ++ operator in Dart?

a. Decrement by 1
b. Increment by 1
c. Multiply by 2
d. Divide by 2

15-In Dart, what does the ??= operator do?

a. Assignment if null
b. Null-aware coalescing assignment
c. Logical OR assignment
d. Logical AND assignment

Explanation:

1-Answer: b. Modulo

The % operator in Dart is used for modulo, which returns the remainder of the division.

2-Answer: b. &&

The && operator is used for logical AND in Dart.

3-Answer: b. 3.33

The result of 10 / 3 in Dart is a floating-point number, approximately 3.33.

4-Answer: b. Not equal to

The != operator is used for “not equal to” comparison in Dart.

5-Answer: a. =

The = operator is used for assignment in Dart.

6-Answer: c. Logical NOT

The ! operator is used for logical NOT in Dart.

7-Answer: a. Greater than or equal to

The >= operator checks if the left operand is greater than or equal to the right operand.

8-Answer: a. ||

The || operator is used for logical OR in Dart.

9-Answer: a. 15

The num *= 3 operation multiplies num by 3. If num is initially 5, the result is 15.

10-Answer: c. true && false

(true && false) || true evaluates to false || true, which is true.

11-Answer: c. ==

The == operator is used for equality comparison in Dart.

12-Answer: b. Null-aware coalescing

The ?? operator is used for null-aware coalescing in Dart.

13-Answer: b. 2

The ~/ operator is the integer division operator in Dart, and 5 ~/ 2 results in 2.

14-Answer: b. Increment by 1

The ++ operator is used for incrementing a variable by 1.

15-Answer: b. Null-aware coalescing assignment

The ??= operator is used for null-aware coalescing assignment in Dart. It assigns the right-hand side to the left-hand side only if the left-hand side is null.

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