How to pass an array via $_GET in php?

How can I pass one or more variables of type array to another page via $_GET?

I alwa开发者_运维问答ys passed variable values in the form ?a=1&b=2&c=3

What about passing a=[1,2,3] ?

Do I need to write a for loop and append all the values?

Thanks

You can use the [] syntax to pass arrays through _GET:

?a[]=1&a[]=2&a[]=3

PHP understands this syntax, so $_GET['a'] will be equal to array(1, 2, 3).

You can also specify keys:

?a[42]=1&a[foo]=2&a[bar]=3

Multidimentional arrays work too:

?a[42][b][c]=1&a[foo]=2

http_build_query() does this automatically:

http_build_query(array('a' => array(1, 2, 3))) // "a[]=1&a[]=2&a[]=3"

http_build_query(array(
    'a' => array(
        'foo' => 'bar',
        'bar' => array(1, 2, 3),
     )
)); // "a[foo]=bar&a[bar][]=1&a[bar][]=2&a[bar][]=3"

An alternative would be to pass json encoded arrays:

?a=[1,2,3]

And you can parse a with json_decode:

$a = json_decode($_GET['a']); // array(1, 2, 3)

And encode it again with json_encode:

json_encode(array(1, 2, 3)); // "[1,2,3]"

Dont ever use serialize() for this purpose. Serialize allows to serialize objects, and there is ways to make them execute code. So you should never deserialize untrusted strings.

You can pass an associative array to http_build_query() and append the resulting string as the query string to the URL. The array will automatically be parsed by PHP so $_GET on the receiving page will contain an array.

Example

$query_str = http_build_query(array(
    'a' => array(1, 2, 3)
));

$city_names = array(
    'delhi',
    'mumbai',
    'kolkata',
    'chennai'
);
$city_query = http_build_query(array('city' => $city_names));

this will give you:

city[0]=delhi&city[1]=mumbai&city[2]=kolkata&city[3]=chennai

if you want to encode the brackets also then use the below code:

$city_query = urlencode(http_build_query(array('city' => $city_names)));

Output:

city%255B0%255D%3Ddelhi%26city%255B1%255D%3Dmumbai .....

Reference: http_build_query, urlencode

Just repeat your $_GET variables like this: name=john&name=lea

This gives you an array.

I used to believe it would be overwritten!