Dart If...Else
Making decisions in your Dart programs
🤔 What is If...Else?
If-else statements allow your program to make decisions by executing different code blocks based on conditions. It's like asking questions and taking different actions based on the answers.
// Simple if-else example
void main() {
int temperature = 25;
if (temperature > 30) {
print('It\'s hot outside!');
} else {
print('It\'s pleasant weather.');
}
}
Types of If Statements
Simple If
Execute code when condition is true
if (age >= 18) {
print('You can vote');
}If-Else
Choose between two options
if (score >= 50) {
print('Pass');
} else {
print('Fail');
}Else If
Multiple conditions to check
if (grade >= 90) {
print('A');
} else if (grade >= 80) {
print('B');
} else {
print('C');
}Ternary Operator
Short form for simple conditions
String result = age >= 18
? 'Adult'
: 'Minor';🔹 Basic If Statement
The simplest form checks one condition:
void main() {
int number = 10;
if (number > 0) {
print('Number is positive');
}
print('Program continues...');
}Output:
Number is positive
Program continues...
🔹 If-Else Statement
Choose between two different actions:
void main() {
int age = 16;
if (age >= 18) {
print('You are eligible to vote');
} else {
print('You are not eligible to vote yet');
}
}Output:
You are not eligible to vote yet
🔹 Multiple Conditions (Else If)
Check multiple conditions in sequence:
void main() {
int marks = 85;
if (marks >= 90) {
print('Grade: A+');
} else if (marks >= 80) {
print('Grade: A');
} else if (marks >= 70) {
print('Grade: B');
} else if (marks >= 60) {
print('Grade: C');
} else {
print('Grade: F');
}
}Output:
Grade: A
🔹 Logical Operators
Combine multiple conditions using logical operators:
void main() {
int age = 25;
bool hasLicense = true;
// AND operator (&&)
if (age >= 18 && hasLicense) {
print('You can drive');
}
// OR operator (||)
if (age < 16 || age > 65) {
print('Special driving rules may apply');
}
// NOT operator (!)
if (!hasLicense) {
print('You need a license to drive');
}
}Output:
You can drive
🔹 Ternary Operator
A shorthand way to write simple if-else statements:
void main() {
int number = 15;
// Traditional if-else
String result1;
if (number % 2 == 0) {
result1 = 'Even';
} else {
result1 = 'Odd';
}
// Ternary operator (shorter)
String result2 = number % 2 == 0 ? 'Even' : 'Odd';
print('Number is: $result2');
}Output:
Number is: Odd