PHP implode
Summary: in this tutorial, you’ll learn how to use the PHP implode() function to join a list of string using a separator.
Introduction to the PHP implode() function
The PHP implode() function allows you to join an array of strings by a separator. Here’s the syntax of the implode() function:
implode ( string $separator , array $array ) : stringCode language: PHP (php)
The implode() function has two parameters:
- The
$separatoris the separator that separates between two strings. The$separatordefaults to an empty string. - The
$arrayis an array of strings to join.
The implode() function returns a new string resulting from joining string elements in the $array with the separator.
The order of string elements in the result string is the same as the order they appear on the $array.
If the array is empty, then the implode() function returns an empty string.
Note that the join() function is the alias of the implode() function so that you can use them interchangeably.
PHP implode() function examples
Let’s take some examples of using the implode() function.
1) Using the implode() function to join strings example
Suppose that you have a list of column names, including first_name, last_name, and email. And you want to turn it into a header of a CSV file.
To do that, you can use the implode() function to join the string elements like this:
$columns = ['first_name', 'last_name', 'email'];
$header = implode(',', $columns);
echo $header;
Code language: PHP (php)
Output:
first_name,last_name,emailCode language: PHP (php)
2) Using the implode() function with the array_map() function
If you want to replace the underscore (_) in each element, you can do it as follows:
$columns = ['first_name', 'last_name', 'email'];
$header = implode(',', array_map(fn ($c) => str_replace('_', ' ', $c), $columns));
echo $header;
Code language: PHP (php)
How it works.
- First, the
array_map()returns a new array with each element’s underscore string (_) replaced by the space. - Second, the
implode()joins the strings of the returned array of the array_map() function.
3) Using the implode() function with the array_filter() function
The following example illustrates how to use the implode() function with the array_filter() function:
$columns = ['ssn', 'first_name', 'last_name', 'password', 'email', 'phone'];
$excludes = ['ssn', 'password'];
$header = implode(',', array_filter($columns, fn ($c) => !in_array($c, $excludes)));
echo $header;
Code language: PHP (php)
Output:
first_name,last_name,email,phoneCode language: PHP (php)
How it works.
- First, define two arrays of strings, one for columns and the other for excluding columns.
- Second, use the
array_filter()function to filter the columns in the excluded list. - Third, use the
implode()function to join the strings in the array returned by thearray_filter()function.
4) Using the PHP implode() function with an associative array example
If you pass an associative array to the implode() function, it will join the array’s values only and disregard the array keys. For example:
$person = [
'first_name' => 'John',
'last_name' => 'Doe',
25,
'Female'
];
echo implode(',', $person);
Code language: PHP (php)
Output:
John,Doe,25,FemaleCode language: PHP (php)
5) Using the PHP implode() function with an array that has one element
The following defines a function called get_header() that returns a comma-separated list of columns:
function get_header(array $columns): string
{
if (1 === count($columns)) {
return $columns[0];
}
return implode(',', $columns);
}
Code language: PHP (php)
The get_header() function returns the first element in the $columns array if the $columns array has one element. Otherwise, it returns a comma-separated list of strings in the $columns array.
The following shows how to use the get_header() function:
echo get_header(['first_name']); // first_name
echo get_header(['first_name', 'last_name']); // first_name,last_name
Code language: PHP (php)
However, the code in the get_header() is unnecessary since the implode() function already has a logic to handle the array with one element. For example:
echo implode(',', ['first_name']); // first_name
echo implode(',', ['first_name', 'last_name']); // first_name,last_name
Code language: PHP (php)
When the input array has one element, the implode() function doesn’t add a trailing separator, which is the comma in this example.
Summary
- Use the PHP
implode()function to join strings in an array with a separator between each element.