PHP Recursive Function

Syntax

A recursive function is a function that calls itself. In PHP, the syntax for a recursive function is as follows:

function recursive_function($parameter){
    // base case
    if($parameter == 0){
        return 1;
    } 
    // recursive case
    else {
        return $parameter * recursive_function($parameter - 1);
    }
}

Example

Here is an example of a recursive function that calculates the factorial of a number:

function factorial($n){
    // base case
    if($n == 0 || $n == 1){
        return 1;
    }
    // recursive case
    else {
        return $n * factorial($n - 1);
    }
}

echo factorial(5); // output: 120

Output

When running the above code, it will output the factorial of the given number.

Explanation

Recursive functions are useful for solving problems that can be broken down into smaller, similar subproblems. In the example above, the factorial of a number is calculated by breaking the problem down to the factorial of a smaller number, until the base case of 0 or 1 is reached.

Use

Recursive functions are used when solving problems that contain repeated subproblems. They are useful for breaking down complex problems into smaller, more manageable ones.

Important Points

• Recursive functions can be used for solving problems that contain repeated subproblems.
• A recursive function calls itself using a base case and a recursive case.
• Recursive functions are useful for breaking down complex problems into smaller, more manageable ones.

Summary

Recursive functions are an important programming concept that allows us to break down complex problems into smaller, more manageable ones. In PHP, recursive functions are used when solving problems that rely on repeated subproblems.