php_mysql_apache [Electronic resources] نسخه متنی

Some Array-Related Functions

Approximately 60 array-related functions are built into PHP, which you can read about in detail at http://www.php.net/array. Some of the more common (and useful) functions are explained in this section.

• count()

  and sizeof()
  Each counts the number of elements in an array. Given the following array:

  
  $colors = array("blue", "black", "red", "green");
  

  both count($colors); and sizeof($colors); return a value of 4.

• each()

  and list()
  These usually appear together, in the context of stepping through an array and returning its keys and values. The following example steps through an associative array called $character, printing its key, the text has a value of, and the value, followed by an HTML break.

  
  while (list($key, $val) = each($characater)) {
  echo "$key has a value of $val <br>";
  }
  

• foreach()
  This is also used to step through an array, assigning the value of an element to a given variable. The following example steps through an associative array called $character, prints some text, the value, and finally an HTML break.

  
  foreach($characater as $c) {
  echo "The value is $c <br>";
  }
  

• reset()
  This rewinds the pointer to the beginning an array, as in this example:

  
  reset($character);
  

  This function is useful when you are performing multiple manipulations on an array, such as sorting, extracting values, and so forth.

• array_push()
  This adds one or more elements to the end of an existing array, as in this example:

  
  array_push($existingArray, "element 1", "element 2", "element 3");
  

• array_pop()
  This removes (and returns) the last element of an existing array, as in this example:

  
  $last_element = array_pop($existingArray);
  

• array_unshift()
  This adds one or more elements to the beginning of an existing array, as in this example:

  
  array_unshift($existingArray, "element 1", "element 2", "element 3");
  

• array_shift()
  This removes (and returns) the first element of an existing array, as in this example:

  
  $first_element = array_shift($existingArray);
  

• array_merge()
  This combines two or more existing arrays, as in this example:

  
  $newArray = array_merge($array1, $array2);
  

• array_keys()
  This returns an array containing all the key names within a given array, as in this example:

  
  $keysArray = array_keys($existingArray);
  

• array_values()
  This returns an array containing all the values within a given array, as in this example:

  
  $valuesArray = array_values($existingArray);
  

• shuffle()
  This randomizes the elements of a given array. The syntax of this function is simply as follows:

  
  shuffle($existingArray);
  

This brief rundown of array-related functions only scratches the surface of using arrays. However, arrays and array-related functions are used in the code examples throughout this book.