Revision 5824dc6f-c17e-4356-9b15-cc9a103291ae - Code Golf Stack Exchange

# [C (gcc)], <sup><s>60</s>\$\cdots\$ <s>55</s></sup> 54 bytes

Saved <s>2</s> 4 bytes thanks to [AZTECCO](https://codegolf.stackexchange.com/users/84844/aztecco)!!! 

Saved <s>a</s> 2 bytes thanks to [ceilingcat](https://codegolf.stackexchange.com/users/52904/ceilingcat)!!! 

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

 #define f(a,b)for(;*a+*b;b+=!!*b)a+=putchar(*a^*b)!=*b

[Try it online!][TIO-kcuti6y5]

[C (gcc)]: https://gcc.gnu.org/
[TIO-kcuti6y5]: https://tio.run/##jVHbToNAEH3vVywY43IxQq1ag9jUtokPJvYS0wepuguLkiAgYEps@u24s0tr2yc3GebsXM6ZZfzTd9@v66OAhVHCUIiJSbUwzbGjE0OnDjVcRdGpRgw3@y79D5JjnbzwgOLqtP4kUYI1tGohfiCpo5IV5St5XiAXrdR7FsepqZpIIgCE@gEDEKdLlvukEBfoAm@3zzsXBwFwlg3fNx@ya@dQjjZy8zSPAwUql4/Th6Fs5IwArnsnSBy4iED36nJPqn83GI4AfBUNmEz@ZtpTZVXGqpIFja5X2aFXWYR7xr3FjXILoLun3yJDkM0mc8H3NB6PpoP@bLQrzsu7ksLqcGsDjYpkwto1KM6yTA4oR25G41tDOEpKFCUBq/hgltPAG1REPywN8WZu7awJiOdoDjIMUblZJZws51whVj31uPC4mPRewmGzY9GyMDc7kFfN2TKE@J@FW6mES4DA9v/ula5b6/oX "C (gcc) – Try It Online"