communication.cpp: In function 'int main()':
communication.cpp:31:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
31 | freopen("input.txt", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
communication.cpp:32:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
32 | freopen("output.txt", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/ccdtfIvN.o: in function `main':
interface.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccB4nDVM.o:communication.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccdtfIvN.o: in function `_do_encode(int, int)':
interface.cpp:(.text+0x1d9): undefined reference to `encode(int, int)'
/usr/bin/ld: /tmp/ccdtfIvN.o: in function `_do_decode(int)':
interface.cpp:(.text+0x219): undefined reference to `decode(int)'
/usr/bin/ld: /tmp/ccdtfIvN.o: in function `main':
interface.cpp:(.text.startup+0xac): undefined reference to `decode(int)'
/usr/bin/ld: interface.cpp:(.text.startup+0x15c): undefined reference to `encode(int, int)'
collect2: error: ld returned 1 exit status