[C] Postfix --> Infix

#include <stdio.h> #include <stdlib.h> #define MAX 20 void push(int *top,float *stack,float item) {         if(*top >= MAX-1) {//overflow                 fprintf(stderr,"\nStack Overflow ");                 exit(1);         }         else {                 stack[++(*top)] =item;         } } float pop(int *top,float *stack) {         float item; // 아이템         if(*top == -1) {//stackunderflow                 fprintf(stderr,"\nStack Underflow");         }         else {                 item = stack[(*top)--]; // 할당 후 top 감소         }         return item; } float oper(int *top,float *stack,char *postfix,int n) {         float r_value,l_value;         for (int i=0 ; i<n-1 ; i++) {                 if ((postfix[i]=='*')||(postfix[i]=='/')||(postfix[i]=='+')||(postfix[i]=='-')) {                         r_value = pop(top,stack); //right_value                         l_value = pop(top,stack); //left_value                         if (postfix[i] == '+') push(top,stack,l_value+r_value);                         else if (postfix[i] == '-') push(top,stack,l_value-r_value);                         else if (postfix[i] == '*') push(top,stack,l_value*r_value);                         else push(top,stack,l_value/r_value);                 }                 else {                         push(top,stack,(float)(postfix[i]-'0'));                 }         }         return pop(top,stack); } int show_menu() {         int order;         printf("=============================================");         printf("\nPostfix로 변환된 식은(234*+56/2*3/-4+)입니다.");         printf("\n1)결과 보기 2)EXIT");         printf("\n=============================================\n");         scanf("%d",&order);         return order;                  } int main() {         char postfix[]="234*+56/2*3/-4+"; //infix -- > postfix로 변환된 식         //char oper[5]={'+','-','*','/'};         float stack[MAX];         int top=-1;         while(1) {                 switch(show_menu()) {                 case 1 :                         printf("\n최종값은 %f\n",oper(&top,stack,postfix,sizeof(postfix)/sizeof(char)));                         break;                 case 2 :                         printf("\n종료\n");                         exit(1);                         }         }         return 0; }