Compilare: user.cpp: In function ‘int main()’: user.cpp:133:15: warning: array subscript has type ‘char’ [-Wchar-subscripts] ++f[ch]; ^ user.cpp:122:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sumall.in", "r", stdin); ^ user.cpp:123:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sumall.out", "w", stdout); ^ user.cpp:129:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c", &ch); ^