Compilare: user.cpp: In function ‘void initDigit()’: user.cpp:28:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] digit[a] = true; ^ user.cpp: In function ‘bool isDigit(char)’: user.cpp:34:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] return digit[c]; ^ user.cpp: In function ‘char readChar(FILE*)’: user.cpp:15:46: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, sizeof(char), BUF_SIZE, f); ^