Compilare: user.cpp: In function ‘int main()’: user.cpp:80:20: warning: left operand of comma operator has no effect [-Wunused-value] for (int i = 3; i <= N, cnt < N; i = add (i, 1), cnt ++) { ^ user.cpp: In function ‘int add(int, int)’: user.cpp:36:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:39:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("oo.in", "r", stdin); ^ user.cpp:40:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("oo.out", "w", stdout); ^ user.cpp:42:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &N); ^ user.cpp:44:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &v[i]); ^