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run code in 300+ PHP versions simultaneously
<?php function fib($m){$j=0;$k=1;for($i=0;$i<=$m;$i++){$l=$k;$k=$j+$k;$j=$l;}return$k;} var_dump(fib(1000));
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
float(1.137969253983602E+209)
Output for 4.3.3 - 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, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.5 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33
float(1.1379692539836E+209)
Output for 4.3.0 - 4.3.2
float(0.E+79)

preferences:
208.65 ms | 401 KiB | 313 Q