Rust - Tuple

Tuple is a compound data type. A scalar type can store only one type of data. For example, an i32 variable can store only a single integer value. In compound types, we can store more than one value at a time and it can be of different types.

Tuples have a fixed length - once declared they cannot grow or shrink in size. The tuple index starts from 0.

Syntax

//Syntax1
let tuple_name:(data_type1,data_type2,data_type3) = (value1,value2,value3);

//Syntax2
let tuple_name = (value1,value2,value3);

Illustration

The following example displays the values in a tuple.

fn main() {
   let tuple:(i32,f64,u8) = (-325,4.9,22);
   println!("{:?}",tuple);
}

The println!("{ }",tuple) syntax cannot be used to display values in a tuple. This is because a tuple is a compound type. Use the println!("{:?}", tuple_name) syntax to print values in a tuple.

Output

(-325, 4.9, 22)

Illustration

The following example prints inspanidual values in a tuple.

fn main() {
   let tuple:(i32,f64,u8) = (-325,4.9,22);
   println!("integer is :{:?}",tuple.0);
   println!("float is :{:?}",tuple.1);
   println!("unsigned integer is :{:?}",tuple.2);
}

Output

integer is :-325
float is :4.9
unsigned integer is :2

Illustration

The following example passes a tuple as parameter to a function. Tuples are passed by value to functions.

fn main(){
   let b:(i32,bool,f64) = (110,true,10.9);
   print(b);
}
//pass the tuple as a parameter

fn print(x:(i32,bool,f64)){
   println!("Inside print method");
   println!("{:?}",x);
}

Output

Inside print method
(110, true, 10.9)

Destructing

Destructing assignment is a feature of rust wherein we unpack the values of a tuple. This is achieved by assigning a tuple to distinct variables.

Consider the following example −

fn main(){
   let b:(i32,bool,f64) = (30,true,7.9);
   print(b);
}
fn print(x:(i32,bool,f64)){
   println!("Inside print method");
   let (age,is_male,cgpa) = x; //assigns a tuple to 
   distinct variables
   println!("Age is {} , isMale? {},cgpa is 
   {}",age,is_male,cgpa);
}

Variable x is a tuple which is assigned to the let statement. Each variable - age, is_male and cgpa will contain the corresponding values in a tuple.

Output

Inside print method
Age is 30 , isMale? true,cgpa is 7.9