What's wrong with the code below? Why does it prompt a syntax error when running?

Question

<?php
 $arr1 = ['id'=>100,'demo'=>"SQ"];
 $arr2 = [1=>100, 1.3=>"SQ", 1.7="SHI", true="Qiang"];
 print_r($arr1);
 print_r($arr2);
?>

Answer 1

Correct solution on the first floor

Answer 2

1.7=>      true=>