Rust Function: Calculate factorial of a number

Rust Functions and Control Flow: Exercise-4 with Solution

Write a Rust function to calculate the factorial of a given number.

Sample Solution:

Rust Code:

// Define a function named 'factorial' that takes a non-negative integer as input and returns its factorial
fn factorial(n: u64) -> u64 {
    // Base case: Factorial of 0 is 1
    if n == 0 {
        return 1;
    }

    // Recursive case: Calculate factorial using recursion
    n * factorial(n - 1)
}

fn main() {
    let n = 5; // Define the number for which factorial is to be calculated

    // Call the 'factorial' function with the specified number
    let result = factorial(n as u64);

    // Print the factorial of the number
    println!("Factorial of {} is: {}", n, result);
}

Output:

Factorial of 5 is: 120

Explanation:

Here's a brief explanation of the above Rust code:

• 'fn factorial(n: u64) -> u64 { ... }': This is a recursive function named 'factorial' that takes a non-negative integer 'n' as input and returns its factorial as a 'u64' (unsigned 64-bit integer). The function calculates the factorial using recursion.
• Base case: If 'n' is 0, the factorial is defined as 1. Therefore, if 'n' equals 0, the function immediately returns 1.
• Recursive case: If 'n' is greater than 0, the function recursively calls itself with 'n-1' and multiplies the result by 'n'.
• 'fn main() { ... }': This is the program's entry point.
• 'let n = 5;': This line defines the number for which the factorial is to be calculated.
• 'let result = factorial(n as u64);': This line calls the 'factorial' function with the specified number ('n') and stores the result in the variable 'result'.
• 'println!("Factorial of {} is: {}", n, result);': This line prints the factorial of the number along with the original number.

Rust Code Editor:

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