3v4l.org

run code in 300+ PHP versions simultaneously
<?php function a () { function b() { echo "I am b.\n"; } echo "I am a.\n"; } echo function_exists("b") ? "b is defined\n" : "b is not defined"; a(); echo function_exists("b") ? "b is defined\n" : "b is not defined"; b();
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, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
b is not definedI am a. b is defined I am b.
preferences:
174.16 ms | 406 KiB | 310 Q