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Rust Programming Language

Solution Review 1: Find The Factorial

Explore how to implement a factorial function in Rust using loops and conditional logic. This lesson helps you understand mutable variables, for loops, and control flow with if-else statements to solve factorial problems effectively.

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Solution

Rust 1.40.0
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);

}

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 ...