PHP/Data Structure/array shift

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array_shift() function operates much like array_pop()

//array_shift() function removes one element from the left side of the array. 
//All remaining array elements are shifted one unit toward the left side of the array. 
//array_shift() has the same syntax as array_pop():
    $languages = array("Spanish", "English", "French", "Russian");
    $a_language = array_shift($languages); 

array_shift( ) function returns the value from the front of the array while also removing it from the array.

    $names = array("Johnny", "Timmy", "Bobby", "Sam", "Tammy", "Joe");
    $firstname = array_shift($names); // "Johnny"

Removing the First Element of an Array with array_shift()

array_shift() removes and returns the first element of an array passed to it as an argument. 
$an_array = array("a", "b", "c");
while ( count( $an_array ) ) {
  $val = array_shift( $an_array);
  print "$val<br />";
  print "there are ".count( $an_array )." elements in \$an_array <br />";

Removing the First or Last Element from an Array

  $languages = array("French","German","Russian","Chinese","Hindi", "Quechua");
  printf("<p>Original array:</p><pre>%s</pre>\n", var_export($languages, TRUE));
  $removed = array_shift($languages);
  printf("<p>Using array_shift():<br />Removed element: %s</p><pre>%s</pre>\n",
          $removed, var_export($languages, TRUE));
  $removed = array_pop($languages);
  printf("<p>Using array_pop():<br />Removed element: %s</p><pre>%s</pre>\n",
          $removed, var_export($languages, TRUE));
  unset( $languages[count($languages) - 1] );
  printf("<p>Using unset() and count():</p><pre>%s</pre>\n",
          var_export($languages, TRUE));