`String` list

In PHP programs we often need to create lists of strings. We need to add more strings in a dynamic way, as program logic proceeds. The array() syntax is useful here.

Once we create a string list in PHP, we will want to iterate over it. The foreach-loop goes from the first to the last element.

Create new

To begin, we create 2 string lists and populate them with elements. We keep this example simple, but show 2 different initialization syntax forms.

Version 1 We use the array() syntax. We pass 3 string elements to the initializer and the result has 3 elements.

Version 2 This is the short syntax for creating string lists (arrays) and because it is easier to read, it should be preferred.

// Version 1: syntax for list of 3 strings.
$array1 = array("bird", "frog", "cat");
var_dump($array1);

// Version 2: another syntax.
$array2 = ["bird", "frog", "cat"];
var_dump($array2);array(3) {
  [0]=>
  string(4) "bird"
  [1]=>
  string(4) "frog"
  [2]=>
  string(3) "cat"
}
array(3) {
  [0]=>
  string(4) "bird"
  [1]=>
  string(4) "frog"
  [2]=>
  string(3) "cat"
}

Foreach example

To continue, we use the foreach-loop to iterate over the string elements. Consider a string list of 3 elements—the loop body will be repeated 3 times.

Part 1 We create the string list with the short, simple syntax—3 elements are present upon creation.

Part 2 We use foreach to iterate over the elements in the string list. Each string (and its length) is printed with var_dump().

// Part 1: create string list of 3 strings.
$systems = ["linux", "mac", "windows"];

// Part 2: use foreach and display the strings.
foreach ($systems as $test) {
    var_dump($test);
}
string(5) "linux"
string(3) "mac"
string(7) "windows"

`Append` `string`

We can append a string to a string list as well in PHP. We use the special "append" syntax, which adds an index past the last current index.

Tip To append to a list, assign to the empty index—the element is placed at the end.

$letters = ["a", "b"];

// Append the value 30 to the list.
$letters[] = "c";
$letters[] = "d";
var_dump($letters);array(4) {
  [0]=>
  string(1) "a"
  [1]=>
  string(1) "b"
  [2]=>
  string(1) "c"
  [3]=>
  string(1) "d"
}

`Reverse` example

Occasionally we may want to reverse the ordering of a string list in PHP. To do this, we can invoke the array_reverse function on a string array.

$words = ["one", "two"];

// Reverse the words in the string array.
$result = array_reverse($words);
var_dump($result);array(2) {
  [0]=>
  string(3) "two"
  [1]=>
  string(3) "one"
}

Notes, arrays

In PHP we implement a string list with an array—but the array type has other features. It can be used as an associative array (a hash) as well.

Using string lists in PHP is nearly universal—most programs will need to store collections of strings. Important program logic relies upon strings.

String list