#define ERR_DEEP_NESTING 1
#define ERR_PAREN_NOT_MATCH 2
#define ERR_NOT_A_NUMBER 3
#define ERR_NULL_FOUND 4
#define ERR_EXCESS_CHARACTERS 5
#define ERR_VAR_UNDEFINED 6
/* prototypes */
void setdegree(void);
void setradian(void);
int evaluate(char**, double*);
