Rust If..Else
Making decisions and controlling program flow
🔀 What is Rust If..Else?
If..else statements in Rust allow your program to make decisions based on conditions. They execute different code blocks depending on whether conditions are true or false, enabling dynamic program behavior.
// Basic if..else example
let age = 18;
if age >= 18 {
println!("You can vote!");
} else {
println!("Too young to vote.");
}
Types of Conditional Statements
Simple If
Execute code when condition is true
if temperature > 30 {
println!("It's hot!");
}If..Else
Choose between two options
if is_sunny {
println!("Go outside!");
} else {
println!("Stay inside!");
}Else If
Multiple conditions in sequence
if score >= 90 {
println!("A grade");
} else if score >= 80 {
println!("B grade");
}If Expression
Return values from if statements
let status = if online {
"Connected"
} else {
"Offline"
};🔹 Basic If Statement
The simplest form of conditional execution:
fn main() {
let temperature = 25;
let is_raining = false;
let has_umbrella = true;
// Simple if statement
if temperature > 20 {
println!("It's a nice day!");
}
// If with boolean variable
if is_raining {
println!("Don't forget your umbrella!");
}
// If with logical operators
if !is_raining && temperature > 15 {
println!("Perfect weather for a walk!");
}
// If with complex condition
if is_raining && has_umbrella {
println!("You're prepared for the rain!");
}
}Output:
It's a nice day!
Perfect weather for a walk!
🔹 If..Else Statement
Choosing between two different actions:
fn main() {
let age = 16;
let has_license = false;
let balance = 50.0;
// Basic if..else
if age >= 18 {
println!("You are an adult.");
} else {
println!("You are a minor.");
}
// If..else with boolean
if has_license {
println!("You can drive!");
} else {
println!("You need a license to drive.");
}
// If..else with comparison
if balance >= 100.0 {
println!("You have enough money for the premium plan.");
} else {
println!("Consider the basic plan for ${:.2}.", balance);
}
// Nested if..else
if age >= 16 {
if has_license {
println!("Ready to drive!");
} else {
println!("Time to get your license!");
}
} else {
println!("Too young to drive.");
}
}Output:
You are a minor.
You need a license to drive.
Consider the basic plan for $50.00.
Time to get your license!
🔹 Else If Chains
Handling multiple conditions in sequence:
fn main() {
let score = 85;
let temperature = 22;
let hour = 14;
// Grade calculation
if score >= 90 {
println!("Grade: A - Excellent!");
} else if score >= 80 {
println!("Grade: B - Good job!");
} else if score >= 70 {
println!("Grade: C - Satisfactory");
} else if score >= 60 {
println!("Grade: D - Needs improvement");
} else {
println!("Grade: F - Please study more");
}
// Weather description
if temperature > 30 {
println!("It's very hot outside!");
} else if temperature > 20 {
println!("Nice and warm weather.");
} else if temperature > 10 {
println!("A bit cool, wear a jacket.");
} else {
println!("It's cold, bundle up!");
}
// Time of day
if hour < 6 {
println!("Very early morning");
} else if hour < 12 {
println!("Morning");
} else if hour < 17 {
println!("Afternoon");
} else if hour < 21 {
println!("Evening");
} else {
println!("Night");
}
}Output:
Grade: B - Good job!
Nice and warm weather.
Afternoon
🔹 If as Expression
Using if statements to return values:
fn main() {
let age = 20;
let is_weekend = true;
let score = 95;
// If expression assigning values
let status = if age >= 18 {
"Adult"
} else {
"Minor"
};
println!("Status: {}", status);
// If expression with calculations
let ticket_price = if age < 12 {
5.0
} else if age >= 65 {
7.0
} else {
10.0
};
println!("Ticket price: ${:.2}", ticket_price);
// If expression with complex logic
let activity = if is_weekend && age >= 18 {
"Go to the club"
} else if is_weekend {
"Play video games"
} else {
"Go to work/school"
};
println!("Suggested activity: {}", activity);
// If expression with function calls
let grade_letter = if score >= 90 {
'A'
} else if score >= 80 {
'B'
} else if score >= 70 {
'C'
} else {
'F'
};
println!("Your grade: {}", grade_letter);
}Output:
Status: Adult
Ticket price: $10.00
Suggested activity: Go to the club
Your grade: A
🔹 Complex Conditions
Combining multiple conditions with logical operators:
fn main() {
let age = 25;
let has_job = true;
let credit_score = 750;
let income = 50000;
let has_debt = false;
// Loan approval logic
if age >= 18 && has_job && credit_score >= 700 {
println!("Pre-approved for loan!");
} else {
println!("Loan application needs review.");
}
// Insurance premium calculation
let is_young_driver = age < 25;
let is_experienced = age > 30;
let has_accidents = false;
if is_young_driver && !has_accidents {
println!("Standard premium for young driver");
} else if is_experienced && !has_accidents {
println!("Discounted premium for experienced driver");
} else if has_accidents {
println!("Higher premium due to accident history");
} else {
println!("Regular premium");
}
// Investment advice
if income > 75000 && !has_debt && age < 40 {
println!("Consider aggressive investment portfolio");
} else if income > 40000 && age >= 40 {
println!("Consider balanced investment portfolio");
} else if has_debt {
println!("Focus on paying off debt first");
} else {
println!("Start with conservative investments");
}
}Output:
Pre-approved for loan!
Regular premium
Start with conservative investments