Compilare: user.cpp: In function ‘int nextInt()’: user.cpp:40:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (; !isDigit[*head]; ++head); ^ user.cpp:41:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (; isDigit[*head]; ++head) ^ user.cpp: In function ‘void putNumber(int)’: user.cpp:82:9: warning: unused variable ‘old’ [-Wunused-variable] char *old = writeHead; ^~~ user.cpp: In function ‘int main()’: user.cpp:91:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(InFile, "r", stdin); ^ user.cpp:92:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(OuFile, "w", stdout); ^