Revision 2e9bbc4c-4247-4ac7-ba5f-a874c9d57498 - Code Golf Stack Exchange

# [C (gcc)], 60 bytes

<!-- language-all: lang-c -->

 f(a,b)char*a,*b;{for(;*a+*b;a+=!!*a,b+=!!*b)putchar(*a^*b);}

[Try it online!][TIO-kcr0nf80]

[C (gcc)]: https://gcc.gnu.org/
[TIO-kcr0nf80]: https://tio.run/##jVHbToNAEH3vV2xJjMvFSGvVGqxNbZv4YGIvMX2QqgssSoKAQFNiw7fjzC6tbZ/cZJgzszPnzDLu2YfrVpVPmeGo7idLNWZojrXx45RaGtMBM73XbELaEd5Rk1WOhVRjrxBZZfXFgoiqZNMgcAQHyXmWv7GXJemRjfLAwzA2FINIhIA5rscRhPGapy7LRIBd6Fvti87lUQKd2cLvu4u3pXUs59RyizgNvSZWrp9mjyPZCIwIbvqnRBwMRKJ7fXUgNbgfjsYIvrMaTKd/Mx2o8iLhRc69WtcuWr5dmAw8B2@COWAedve1O6ILsvl0IfieJ5PxbDiYj/fFobwrKcwOWBtpFCIvzH3D4iRJ5IBy5Ho0WByhQZSTIPJ4AYOZVg1vSRb88Nin27nV8zohnqNaRNdF5XaVeJIUuHyq2MpJZoOY9HYEsN6xaFka2x3IULV2DD79Z@FOKgIJFNj934PSslFWvw "C (gcc) – Try It Online"