Strings

Strings are variables that hold text. For example, a string which contains a name is defined as follows:

$name = "John";
echo $name;

We can easily format strings using variables. For example:

$name = "John";
$introduction = "Hello $name";
echo $introduction;

We can also concatenate strings using the dot . operator. For example:

$first_name = "John";
$last_name = "Doe";
$name = $first_name . " " . $last_name;
echo $name;

To measure the length of a string, we use the strlen function:

$string = "The length of this string is 43 characters.";
echo strlen($string);

To cut a part of a string and return it as a new string, we can use the substr function:

$filename = "image.png";
$extension = substr($filename, strlen($filename) - 3);
echo "The extension of the file is $extension";

Joining and splitting

We can join arrays to form strings, or split strings to arrays of strings.

For example, to split a string with a list of fruits separated by a comma, we use the explode function:

$fruits = "apple,banana,orange";
$fruit_list = explode(",", $fruits);
echo "The second fruit in the list is $fruit_list[1]";

To join back an array to a single string separated with commas, we use the implode function:

$fruit_list = ["apple","banana","orange"];
$fruits = implode(",", $fruit_list);
echo "The fruits are $fruits";

Exercise

Split string that contains the list of numbers into a new array called number_list.