PHP comma separated string conversion array

In PHP programming, we often encounter situations where we need to convert a string separated by commas (or other delimiters) into an array. This situation is especially common when reading data from the database, because we often store multiple values ​​separated by commas to facilitate querying and filtering.

To this end, PHP provides a series of functions for converting strings into arrays. Let's learn one of them together: explode().

1. explode() function introduction

Theexplode() function is a built-in string function in PHP, mainly used to split a string into an array. Its basic syntax is:

array explode(string $delimiter, string $string, int $limit = PHP_INT_MAX);

Among them, the parameter $delimiter represents the delimiter to be used; the parameter $string represents the string to be divided; the parameter $limit represents the maximum number of divisions. When the delimiter does not appear in the corresponding string, the function returns an array containing the original string as the only element; when the $limit parameter is set to a non-positive number, the number of divisions will not be limited.

2. Use the explode() function to convert a string into an array

The following example shows how to use the explode() function to convert a comma-separated string into an array:

$str = "apple,orange,banana,grape";
$array = explode(",", $str);
print_r($array);

The above code will output:

Array
(
    [0] => apple
    [1] => orange
    [2] => banana
    [3] => grape
)

3. Use the implode() function to convert the array into a string

In practical applications, we also need Convert array to string. PHP also provides the implode() function to implement this function. The usage method is very simple. The example is as follows:

$array = array("apple", "orange", "banana", "grape");
$str = implode(",", $array);
echo $str;

The code output result is:

apple,orange,banana,grape

4. Use serialize() and unserialize () function converts an array into a string and reverses it

In addition to using the implode() function, we can also use the serialize() function to convert an array into a string. Compared with the implode() function, the serialize() function can handle more complex data types, and the string converted from the array can be restored to the original array through the unserialize() function.

The example is as follows:

$array = array("apple", "orange", "banana", array("pear", "peach"));
$str = serialize($array);
echo $str;
$new_array = unserialize($str);
print_r($new_array);

The above code will output:

a:4:{i:0;s:5:"apple";i:1;s:6:"orange";i:2;s:6:"banana";i:3;a:2:{i:0;s:4:"pear";i:1;s:5:"peach";}}
Array
(
    [0] => apple
    [1] => orange
    [2] => banana
    [3] => Array
        (
            [0] => pear
            [1] => peach
        )

)

5. Summary

In PHP programming, separate commas Converting a string into an array is a very common task. We can achieve this quickly and easily by using PHP's built-in string function explode(). In addition, we can also use the implode() function to convert the array into a string, or use the serialize() and unserialize() functions to achieve more complex data conversion.

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