후위 표기식 계산

#include<stdio.h> #include<stdlib.h> #include<string.h> #define TRUE 1 #define FALSE 0 #define MAX_STACK_SIZE 100 typedef char element; typedef struct{ element stack[MAX_STACK_SIZE]; int top; }StackType; void init(StackType *s){ s->top = -1; } int is_empty(StackType *s){ return (s->top == -1); } int is_full(StackType *s){ return (s->top == (MAX_STACK_SIZE-1)); } void push(StackType *s,element item){ if( is_full(s)){ fprintf(stderr,"스택포화에러\n"); return; } else s->stack[++(s->top)] = item; } element pop(StackType *s){ if( is_empty(s)){ fprintf(stderr,"스택공백에러\n"); exit(1); } else return s->stack[(s->top)]; } int eval(char exp[]){ int op1,op2,value,i=0; int len = strlen(exp); char ch; StackType s; init(&s); for ( i=0; i<len; i++){ ch = exp[i]; if( ch != '+' && ch != '-' && ch != '*' && ch != '/' ){ value = ch - '0'; push(&s,value); } else{ op2 = pop(&s); op1 = pop(&s); switch(ch){ case '+' : push(&s,op1+op2); break; case '-' : push(&s,op1-op2); break; case '*' : push(&s, op1*op2); break; case '/' : push(&s, op1/op2); break; } } } return pop(&s); } int main(void){ int result; result = eval("82/3-32*+"); printf("%d\n", result); return 0; }