Compilare: user.cpp: In function ‘int main()’: user.cpp:80:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (C[sstr[i]] == 0) ^ user.cpp:81:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] C[sstr[i]] = pos++; ^ user.cpp:85:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] O[0][i] = C[str[i]]; ^ user.cpp:65:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("substr.in", "r", stdin); ^ user.cpp:66:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("substr.out", "w", stdout); ^ user.cpp:67:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("debug.err", "w", stderr); ^