# C, <s> 62 </s> <s> 58 </s> 54 bytes *Thanks to @Dennis for saving <s> four </s> eight bytes!* f(char*s){s[1]>32||(*s^=s[-1]^=*s^=s[-1]);*++s&&f(s);} [Try it online!](https://tio.run/##XZBBa8MwDIXv/hWCQRun7Vg7tkuWQmEbO/Q0ehlZCsFRYjPXCZFDDm1@e2a3I4EJHcR7Tx9CYlUKMQxFIGTWhMTPlKzT7ePmcglCOsaUrNbpMR5HHoWLBc1mRUA86oc7ZYRuc4QXsrmq7uWWMWUsnDJlAs7ODFx5MpBtks3TcxpdpU4qjRAUJVoKnLUE5y3BQwzn18ht15cHaog9QqPxcR5NZgFeSbQ7DuIY5t9mzkd3gviacvAwEfpxKv6x6/Z23Z/Us344yMzQD/uqWmygQy0qPLGDVASuMwNZXWtk71rVtSoN7NFapAZ2TdXmhtkPhOo1dx/Z7fWbwRI6JS1Q59bcE/U1/fkL)