Compilare: user.cpp: In function ‘void Read(int&)’: user.cpp:12:14: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] char a = NULL; ^ user.cpp: In function ‘int main()’: user.cpp:21:13: warning: unused variable ‘l’ [-Wunused-variable] int i,j,l,ok,x,aux,len; ^ user.cpp:21:24: warning: unused variable ‘len’ [-Wunused-variable] int i,j,l,ok,x,aux,len; ^ user.cpp:22:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("raco.in","r",stdin); ^ user.cpp:23:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("raco.out","w",stdout); ^