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<?php $arr = ['cat' => '14', 'dog' => 14]; var_dump(json_encode($arr));
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.30, 8.2.0 - 8.2.24, 8.3.0 - 8.3.12
string(21) "{"cat":"14","dog":14}"

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84.36 ms | 408 KiB | 5 Q