Compilare: user.cpp: In function 'int can_eval(int)': user.cpp:34: warning: array subscript has type 'char' user.cpp:34: warning: array subscript has type 'char' user.cpp:51: warning: array subscript has type 'char' user.cpp: In function 'int main()': user.cpp:119: warning: comparison between signed and unsigned integer expressions /tmp/ccZvqoyC.o: In function `main': user.cpp:(.text+0x3a9): warning: the `gets' function is dangerous and should not be used.