Write a function to calculate the factorial of a number (a non-negative integer). The function accepts the number as an argument.

PHP / Class, Object and Methods

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Given Input:

Enter a non-negative integer: 5

Expected Output:

5x4x3x2x1=120

Program:

<?php
 /* Enter your code here. Read input from STDIN. Print output to STDOUT */
 
// Function to calculate the factorial of a number
function factorial($n) {
    if ($n < 0) {
        return "Invalid Argument";
    }
    $result = 1;
    $factorial_string = "";
    for ($i = $n; $i > 0; $i--) {
        $result *= $i;
        $factorial_string .= "$i" . ($i != 1 ? "x" : "");
    }
    return "$factorial_string=$result";
}

// Read user input from standard input
// echo "Enter a non-negative integer: ";
$input = trim(fgets(STDIN));

// Convert user input to integer
$n = intval($input);

// Calculate factorial and print output
echo factorial($n);

Output:

Enter a non-negative integer: 5
5x4x3x2x1=120

Explanation:

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