PHP Functions Custom Functions: Create flexible and scalable code

PHP Custom functions are created through the function keyword, which can improve code modularity and reusability: Creation method: Use the function keyword, function name and parameters to create a function. Calling method: Enter the function name and pass parameters to call the function. Practical case: Use a custom function to count the number of prime numbers in a specified range, such as countPrimes(1, 100) to return the number of prime numbers in the range (25).

PHP Functions Custom functions: Create flexible and scalable code

Custom functions are a method created in PHP Powerful way to customize logic blocks. They make code more modular, reusable, and easier to maintain.

Create a custom function

To create a custom function, use the function keyword, followed by the function name and parameters.

function sum($a, $b) {
  return $a + $b;
}

Call a custom function

To call a custom function, just enter the function name and pass the necessary parameters.

$result = sum(5, 10); // Ergebnis 15

Practical case: Calculating the number of prime numbers

Suppose you need a function that calculates the number of prime numbers in a given range. You can easily implement this using a custom function:

function countPrimes($start, $end) {
  $count = 0;
  for ($i = $start; $i <= $end; $i++) {
    if (isPrime($i)) {
      $count++;
    }
  }
  return $count;
}

function isPrime($number) {
  if ($number <= 1) {
    return false;
  }
  for ($i = 2; $i <= sqrt($number); $i++) {
    if ($number % $i == 0) {
      return false;
    }
  }
  return true;
}

Using a custom function

Now you can use the countPrimes() function to count the number of prime numbers in any range:

$primeCount = countPrimes(1, 100); // Ergebnis 25

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