This course provides the best approach to learn Rust, starting from the basics and advancing to complex topics. It is an introduction to Rust for beginners aspiring to become skilled Rust developers.

The word is out: developers love Rust. It's rapidly becoming a top choice for systems and embedded programmers, and the demand for Rust developers is rising. Known for its performance, reliability, and productivity—especially compared to C++—Rust is a powerful language to master. If you're a systems developer, it's a fantastic next step.
In this course, you'll learn Rust by actively engaging in coding. You’ll start with a simple "Hello world" program and cover essential concepts like arrays, strings, vectors, enums, structures, traits, generics, functions, and logic. You'll also dive into advanced topics such as lifetime and memory management.
By the end of this course, you'll have a solid foundation in Rust programming and be well-prepared to take on more advanced concepts, making it ideal for Rust beginners looking to become proficient Rust developers.

Rust Programming Language

fn test(n:i32) {
   let mut factorial = 1; // define a mutable variable factorial

   if n < 0 { // check if factorial is less than zero
      println!("0"); // print 0
   }
   else if n == 0 {  // check if factorial is equal to 0
      println!("1"); // print 1
   }
   else // go here if the above two conditions are false
   {
      for i in 1..n + 1{
         factorial = factorial * i  
      }
      println!("{}", factorial); // print the factorial 
   }
}
fn main(){
    print!("factorial (4) : ");
    test(4);
    print!("factorial (6) : ");
    test(6);
}

#[allow(unused_variables, unused_mut)]
#[allow(dead_code)]



fn test(n:i32) {
   let mut factorial = 1;

   if n < 0{
      println!("0");
   }
   else if n == 0{
      println!("1");
   }
   else
   {
      for i in 1..n + 1{
         factorial = factorial*i
      }
      println!("{}",factorial);
   }
}

## Explanation
* On **line 2** a mutable variable `factorial` is initialized to `1`.
* **`if` construct**
   * As factorials exist only for positive numbers, the condition `n < 0 ` on **line 4**, checks if the value of input number `n`
   is less than 0 , it *prints 0* on **line 5**.

     if the **`if` condition fails** then `else if` is executed.
 
* **`else if` construct**
   
   * As the factorial of 0 is 1, the condition `n == 0 ` on **line 7**, checks if the value of input number `n` is equal to 0 then it *prints 1* on **line 8**.

     if the **`else if` condition fails** then `else` block is executed.

* **`else` construct**

   
  * A **`for` loop** is defined within the else block.
     * `for` loop definition
        
       On **line 12**, the `for` loop iterates from 1 to `n+1` times.
    * `for` loop body
      * Within each iteration, on **line 13** `factorial` is multiplied with `i` and the updated value is saved in `factorial`.  
      * The loop iterates until the `i` is equal to `n + 1`.
   
   * The value of `factorial` is printed on **line 15**.



The following illustration explains the above code. 

>Assume that the variable `n` is initialized with value 4 and passed to the function.

This lesson gives a detailed solution review to the challenge in the previous lesson.

Introduction to Rust

Rust Programs

Rust Variables

Rust Data Types

Rust Operators

Rust if and if let Expressions

Rust Loops

Rust Functions

Rust Strings

Rust Vectors

Rust Structs

Conclusion

Rust Exam

Solution Review 1: Find The Factorial