The PHP builtin function implode(), is used to join the elements of an array with a separator string.

The syntax of implode:

implode(string $separator, array $array): string

Parameters
separator: It is an optional parameter and its default value is an empty string.
array: It is an array of strings to implode

Examples of implode are:

1. An Array to string 

$colors = [ 'red', 'white', 'blue', 'black' ];
$colors = implode( ", ",$colors );
echo 'Colors are: '.$colors;

Output

2. An Associative array to string

It is complex to join the key and value of an associative array using only implode function. Combining array_walk() and implode() functions of the PHP will make the job easier.

The array_walk() function walks through each element of an array in a user-defined callback function regardless of pointer position.

array_walk(array|object &$array, callable $callback, mixed $arg = null): bool

Parameters
array: The input array.
callback: Typically, a callback takes on two parameters. The array parameter’s value is the first, and the key/index second.
arg: arg is an optional parameter. If the callback function requires more than 2 parameters, the arg parameter is supplied. It is passed as the third parameter to the callback.

    $style = [
        'color' => 'red',
        'background-color' => 'blue'
    ];
    array_walk($style, function(&$value, $key) {
        $value = "{$key}:{$value}";
    });
    $divStyle = 'style="'.implode(';', $style).'"';
    echo 'You can use this style in div: ‘. $divStyle;

Output

3. Multidimensional array to string

$style = [
    'Color' => ['red','blue','green','red'],
    'Shape' => ['rectangle','square','triangle','diamond']
];
array_walk($style, function(&$value, $key) {
    $value = implode(', ',$value);
    $value = "{$key}: {$value}";
});


echo implode('<br/>',$style);

Output

 

 

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