Compilare: user.cpp: In function ‘bool eval()’: user.cpp:50: warning: array subscript has type ‘char’ user.cpp: In function ‘int main()’: user.cpp:102: warning: array subscript has type ‘char’ user.cpp:102: warning: array subscript has type ‘char’ user.cpp:58: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:59: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:60: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result user.cpp:97: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:101: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘bool eval()’: user.cpp:40: warning: ‘r’ may be used uninitialized in this function