How to Compile Error When Printing an Integer in Rust

1. Compilation Error in Rust
2. Access a Field on a Primitive Type in Rust
3. Add Two Integers in Rust

This article is about avoiding compile errors when trying to print an integer in Rust v0.13.0.

Compilation Error in Rust

A compilation error occurs when a compiler struggles to build a portion of computer program source code, either because of flaws in the code or, more often, because of compiler problems.

To avoid the compilation error in Rust v0.13.0, we need to explicitly give an integer type.

Example Code:

fn main(){
    let x = 10;
    println!("x = {}", x);
}

Output:

x = 10

The code will work in the new compiler with Rust v0.13.0; we do not need to specify i32 explicitly. However, we can use i32 to print the integer without compilation error.

Example Code:

fn main(){
    let x: i32 = 15;
    println!("x = {}", x);
}

Output:

x = 15

Access a Field on a Primitive Type in Rust

Code example with error:

let x: u32 = 0;
println!("{}", x.foo);

The above code has errors, and it does not print the integers.

The right code for printing the value of integers is:

// We declare a struct called `Foo`, which contains two fields:
struct Foo {
    x: u32,
    y: i64,
}

fn main()
{
    let variable = Foo { x: 0, y: 1 };
    println!("x: {}, y: {}", variable.x, variable.y);

}

We declare a struct called Foo, which contains two fields: x and y. We created an instance of Foo to access its fields.

Output:

x: 0, y: 1

Add Two Integers in Rust

The compile error can be avoided using the code below for adding two integers and printing its result.

Example Code:

fn main() {
  let x: i32 = 20;
  let y: i32 = 40;

  let sum = return_sum(x,  y);
  println!("The sum is = {}", sum);
}

fn return_sum(i: i32, j: i32) -> i32 {
  i + j
}

Output:

The sum is = 60