Compilare: main.cpp: In function 'int main()': main.cpp:48:12: warning: unused variable 'u1' [-Wunused-variable] double u1,u2; ^~ main.cpp:48:15: warning: unused variable 'u2' [-Wunused-variable] double u1,u2; ^~ main.cpp: In function 'int read()': main.cpp:33:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&ch); ^ main.cpp: In function 'int main()': main.cpp:45:33: 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:46:35: 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); ^