Declaring Functions

Part of the Fundamentals section of Coddy's Rust journey. Lesson 49 of 75.

A function is a sequence of code that has a name. The purpose of a function is to reuse a piece of code multiple times.

For example, take a look at this code:

println!("Welcome to Coddy");
println!("New session...");
println!("Welcome to Coddy");
println!("Another session...");
println!("Welcome to Coddy");

We use the same code println!("Welcome to Coddy") over and over again. Another issue with this code is that if we wanted to change the message: Welcome to Coddy to something different, like "Welcome aboard" it would have to change 3 different lines of code. To solve this issue, we will use functions.

To declare a function, we use the following syntax:

fn function_name(parameters) {
	// code
}

For our example, we will create a function named greet and it will look like this:

fn greet() {
    println!("Welcome to Coddy");
}

To use/call/execute the function, we write greet();:

greet();
println!("New session...");
greet();
println!("Another session...");
greet();

This will result in the same output as above.

Note: In Rust, the compiler allows you to call a function before it is declared in the file. However, it is recommended convention to write the function definition before its call/execution.

Challenge

Easy

Write a program that gets one input, a number. The input number indicates how many times to execute the below function.

Create a function that calculates the sum of all of the numbers between 1 and 1000 (including) and prints it, name the function however you like.

Note! As a recommended convention, write the function before its call/execution statements in your code.

Try it yourself

use std::io;

// Function declaration
fn sum_numbers() {
    // Complete Function
    
}


fn main() {
    let mut input = String::new();
    io::stdin().read_line(&mut input).unwrap();
    let n: i32 = input.trim().parse().unwrap();
    for _ in 0..n {
        // Call the function n times
    }
}