# PHP function Exercises: Create a function to calculate the factorial of positive a number

## PHP function: Exercise-1 with Solution

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

**Visual Presentation:**

**Sample Solution: **

**PHP Code:**

```
<?php
// Function to calculate the factorial of a number
function factorial_of_a_number($n)
{
// Base case: if n is 0, return 1 (factorial of 0 is 1)
if ($n == 0)
{
return 1;
}
else
{
// Recursive call: calculate factorial by multiplying n with factorial of (n-1)
return $n * factorial_of_a_number($n - 1);
}
}
// Call the function and print the result
print_r(factorial_of_a_number(4) . "\n");
?>
```

Output:

24

**Explanation:**

In the exercise above,

- Define a function named "factorial_of_a_number()" which takes an integer parameter '$n'.
- Inside the function, there's a conditional check to handle the base case: if the input number '$n' is 0, the function returns 1, as the factorial of 0 is defined to be 1.
- If the input number is not 0, the function recursively calls itself with the argument '$n - 1' and multiplies the result with '$n'.
- The recursive calls continue until the base case is reached (i.e., '$n' becomes 0), at which point the function returns 1.
- Outside the function definition, the "factorial_of_a_number()" function is called with an argument of 4, which calculates the factorial of 4.
- The result is then printed using "print_r()", followed by a newline character ("\n").

**Flowchart : **

**PHP Code Editor:**

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