Arrays in PHP

Producing Arrays

       An array variable can store multiple items of data sequential array elements that are number starting at zero . So the first array is value stored in array element number zero Individual array elements value can be referenced using the variables name followed by the index number in square brackets . 

      for example 

               $months[0] reference value stored in the first  array element 

               $months[1] reference value stored in second array element 

Variable array can be created multiple statement that assign value to successive element 

      array() function to fill the element 

for example 

        $months[]='January';

        $months[]='February';

        $months[]='March';

        $months = array ('January','February','March');

When creating an array you can optionally specify a key name for each element that can be used to reference that element value 

  for example 

         $months['jan']='January';

         $months['feb']='February';

         $months['mar']='March';

   $months=array('jan'=>'January','feb'=>'February','mar'=>'March');

All elements of array can be accessed using a foreach loop  to element value in turn and assign it to a variable 

for example 

         foreach ($months as $value )

            {

                # Use the current $value on each iteration 

             }

The keys can also be accessed on each iteration of the loop using 

     for example 

           foreach ($months as $key =>$value)

                {

                     # Use the current $key and $value on each iteration

                 }

PHP Program

     

        <?php

               

             $day =array('Monday','Tuesday','Wednesday');

             foreach ($day as $value)

               {

                   echo "&bull; $value";

               }

         ?>

  <?php

    

      $months=array('jan'=>'January','feb'=>'February','mar'=>'March');

      foreach ($months as $key =>$value)

         {

               echo "<dl>$key <dd>$value";

          }

  ?>

Sorting Arrays 

      PHP provides two simple function to converts between variable array and string because they are continiously used .

The implode() function converts an array to string and inserts a specified separator between each value

for example 

      $csv_list = implode(','.$array);

The explode() function converts a string to an array by specifying a seprator around which to brek up the string 

for example 

       $array = explode(','.$csv_list);

PHP provides three useful function to sort array element into ascending alphanumeric order 

1 . sort() function - sort by value discarding the original key 

2 . asort() function - sorts by value retaining the original key

3 . ksort() function - sort by key 

PHP Program

   

    <?php

          

         $cars = array('Dodge'=>'Viper','Chevrolet'=>'Camaro','Ford'=>'Mustang');

          echo "Original Element Order ';

           foreach($cars as $key=>$value)

              {

                 echo '&bull', $key. ' ' . $value;

               }

             asort($cars)

             echo " Sorted Into Value Order";

             foreach($cars as $key=>$value)

               {

                  echo '&bull' , $key . ' ' .$value;

                }

             ksort($cars)

               echo "Sorted Into Key Order";

               foreach($cars as $key => $value )

                 {

                    echo '&bull;' , $key . ' ' . $value ;

                  }

     ?>