How to access json file element - php

Question

So I am retrieving a json file from an API, and I want to grab the data from object 'place_id'.
I have been looking online and I have seen how to grab elements from json files, however I can't understand what I am doing wrong, as my code gives me an error:
Warning: Undefined array key "place_id" in C:\xampp\htdocs\cw\tester.php on line 15
This is my php code where I try to grab the data from 'place_id':
$place_json = file_get_contents('https://maps.googleapis.com/maps/api/geocode/json?address=belfast+zoo&key=' . $place_id_key);
$json = json_decode($place_json, true);
echo $json['results']['place_id'];
this is my json file:
{
"results" : [
{
"address_components" : [
{
"long_name" : "Antrim Road",
"short_name" : "Antrim Rd",
"types" : [ "route" ]
},
{
"long_name" : "Belfast",
"short_name" : "Belfast",
"types" : [ "locality", "political" ]
},
{
"long_name" : "Newtownabbey",
"short_name" : "Newtownabbey",
"types" : [ "postal_town" ]
},
{
"long_name" : "Belfast",
"short_name" : "Belfast",
"types" : [ "administrative_area_level_2", "political" ]
},
{
"long_name" : "Northern Ireland",
"short_name" : "Northern Ireland",
"types" : [ "administrative_area_level_1", "political" ]
},
{
"long_name" : "United Kingdom",
"short_name" : "GB",
"types" : [ "country", "political" ]
},
{
"long_name" : "BT36 7PN",
"short_name" : "BT36 7PN",
"types" : [ "postal_code" ]
}
],
"formatted_address" : "Antrim Rd, Belfast, Newtownabbey BT36 7PN, UK",
"geometry" : {
"location" : {
"lat" : 54.6577821,
"lng" : -5.943665699999999
},
"location_type" : "GEOMETRIC_CENTER",
"viewport" : {
"northeast" : {
"lat" : 54.65913108029149,
"lng" : -5.942316719708497
},
"southwest" : {
"lat" : 54.6564331197085,
"lng" : -5.945014680291502
}
}
},
"place_id" : "ChIJ88iCe5inYUgRdeXmfCtuvu4",
"plus_code" : {
"compound_code" : "M354+4G Belfast, UK",
"global_code" : "9C6PM354+4G"
},
"types" : [ "establishment", "point_of_interest", "tourist_attraction", "zoo" ]
}
],
"status" : "OK"
}
Apologies as I know it is obvious, but I can't seem to understand why! thanks!

Answer 1

This should do the trick? Notice the [0] that was added. Since results is actually an array.
<?php
$place_json = file_get_contents('https://maps.googleapis.com/maps/api/geocode/json?address=belfast+zoo&key=' . $place_id_key);
$json = json_decode($place_json, true);
echo $json['results'][0]['place_id'];