Rust by Example: If/Else

The if statement assesses a conditional expression, determining the control flow based on whether the expression evaluates to true or false.
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fn main() {

If/else statements are similar to other languages.

 
    if true {
        println!("true");
    } else if false {
        println!("false");
    } else {
        println!("neither");
    }

Rust supports six comparison operators: ==, !=, <, >, <=, >=. and two boolean operators: && (and) and || (or).

 
    let n = 42;
    if n > 0 && n < 100 {
        println!("n is between 0 and 100");
    } else if n < 0 || n > 100 {
        println!("n is not between 0 and 100");
    }

The if statement can return a value and can be used in a let statement.

 
    let condition = true;
    let number = if condition { 5 } else { 6 };
    println!("The value of number is: {}", number);

Using if let expression, control is determined through pattern matching instead of a conditional expression.

 
    let result: Option<i32> = Some(42);
    if let Some(value) = result {
        println!("The value is: {}", value);
    } else {
        println!("There is no value");
    }
}

$ rustc if-else.sh
$ ./if-else
true
n is between 0 and 100
The value of number is: 5
The value is: 42
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