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run code in 300+ PHP versions simultaneously
<?php $a = 'foo bar baz'; $b = 'a'; var_dump( $$b[0] ); $$b[0] = ''; var_dump( $$b[0] );
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
string(1) "f" Fatal error: Uncaught Error: Cannot assign an empty string to a string offset in /in/DknNV:5 Stack trace: #0 {main} thrown in /in/DknNV on line 5
Process exited with code 255.
Output for 7.1.0 - 7.1.25, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33
string(1) "f" Warning: Cannot assign an empty string to a string offset in /in/DknNV on line 5 string(1) "f"
Output for 7.0.0 - 7.0.20
string(1) "f" string(1) ""
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.28
string(11) "foo bar baz" string(0) ""

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