Compilare: user.cpp: In function ‘int add(int)’: user.cpp:15:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:25:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("inv.in","r",stdin); ^ user.cpp:26:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("inv.out","w",stdout); ^ user.cpp:28:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^ user.cpp:31:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &val); ^