Compilare: user.cpp: In function ‘int main()’: user.cpp:54:17: warning: unused variable ‘dif’ [-Wunused-variable] int i,n,k,w,dif,sum,a,b; ^~~ user.cpp:54:21: warning: unused variable ‘sum’ [-Wunused-variable] int i,n,k,w,dif,sum,a,b; ^~~ user.cpp:54:25: warning: unused variable ‘a’ [-Wunused-variable] int i,n,k,w,dif,sum,a,b; ^ user.cpp:54:27: warning: unused variable ‘b’ [-Wunused-variable] int i,n,k,w,dif,sum,a,b; ^ user.cpp:55:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nmult.in","r",stdin); ^ user.cpp:56:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nmult.out","w",stdout); ^ user.cpp: In function ‘char getChar()’: user.cpp:18:28: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(BUF,LIM,1,stdin); ^