﻿ PHP Function Exercise: Create a function to calculate the factorial of a positive number - w3resource # PHP function Exercises: Create a function to calculate the factorial of positive a number

## PHP function: Exercise-1 with Solution

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

Pictorial Presentation: Sample Solution:

PHP Code:

``````<?php
function factorial_of_a_number(\$n)
{
if(\$n ==0)
{
return 1;
}
else
{
return \$n * factorial_of_a_number(\$n-1);
}
}
print_r(factorial_of_a_number(4)."\n");
?>
```
```

Sample Output:

```24
```

Flowchart : PHP Code Editor:

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## PHP: Tips of the Day

Get first key in a (possibly) associative array?

Starting from PHP 7.3, there is a new built in function called array_key_first() which will retrieve the first key from the given array without resetting the internal pointer. Check out the documentation for more info.

You can use reset and key:

```reset(\$array);
\$first_key = key(\$array);
```

It's essentially the same as your initial code, but with a little less overhead, and it's more obvious what is happening.

Just remember to call reset, or you may get any of the keys in the array. You can also use end instead of reset to get the last key.

If you wanted the key to get the first value, reset actually returns it:

`\$first_value = reset(\$array);`

There is one special case to watch out for though (so check the length of the array first):

```\$arr1 = array(false);
\$arr2 = array();
var_dump(reset(\$arr1) === reset(\$arr2)); // bool(true)
```

Ref : https://bit.ly/32ecxHN