Rust Match
match
When you have many choices, using match is easier than writing lots of if...else.
match is used to select one of many code blocks to be executed:
Example
fn main() {
let day = 4;
match day {
1 => println!("Monday"),
2 => println!("Tuesday"),
3 => println!("Wednesday"),
4 => println!("Thursday"),
5 => println!("Friday"),
6 => println!("Saturday"),
7 => println!("Sunday"),
_ => println!("Invalid day."),
}
}
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Example explained:
- The
matchvariable (day) is evaluated once. - The value of the day variable is compared with the values of each "branch"
- Each branch starts with a value, followed by
=>and a result - If there is a match, the associated block of code is executed
_is used to specify some code to run if there is no match (likedefaultin other languages).- In the example above, the value of day is 4, meaning "Thursday" will be printed
Multiple Matches
You can match multiple values at once using the | operator (OR):
Example
fn main() {
let day = 6;
match day {
1 | 2 | 3 | 4 | 5 => println!("Weekday"),
6 | 7 => println!("Weekend"),
_ => println!("Invalid day"),
}
}
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match with a Return Value
Just like if, match can also return a value:
This means you can save the result of a match into a variable:
Example
fn main() {
let day = 4;
let result = match day {
1 => "Monday",
2 => "Tuesday",
3 => "Wednesday",
4 => "Thursday",
5 => "Friday",
6 => "Saturday",
7 => "Sunday",
_ => "Invalid day.",
};
println!("{}", result);
}
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Note: Each part of the match branches must be the same type - just like with if...else.
