Compilare: main.cpp: In function 'int main()': main.cpp:61:12: warning: unused variable 'u1' [-Wunused-variable] double u1,u2; ^~ main.cpp:61:15: warning: unused variable 'u2' [-Wunused-variable] double u1,u2; ^~ main.cpp: In function 'char ad()': main.cpp:38:33: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buffer,1,sz,stdin); ^ main.cpp: In function 'int main()': main.cpp:58:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("rays.in","r",stdin); ^ main.cpp:59:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("rays.out","w",stdout); ^