rostom

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>

#define TYPE int
#define MAXSIZE 200

typedef struct Stack
{
    int top;
    TYPE data[MAXSIZE];

} Stack;

void reset(Stack *s);
int isEmpty(Stack *s);
int isFull(Stack *s);
void push(Stack *s,TYPE val);
TYPE pop(Stack *s);
void display(Stack s);
int chckop(char x);

int main()
{
    Stack s;
    reset(&s);
    int i;
    char x[100];
    scanf("%s",x);
    for(i=0;i<strlen(x);i++) {
        if(isalnum(x[i])) {
            push(&s,x[i]-48);
        } else {
            int x1;
            int x2;
            x1=pop(&s);
            x2=pop(&s);
            if(chckop(x[i])==1) push(&s,x1+x2);
            else if(chckop(x[i])==2) push(&s,x1-x2);
            else if(chckop(x[i])==3) push(&s,x1*x2);
            else if(chckop(x[i])==4) push(&s,x1/x2);
        }
    }
    printf("%d",s.data[s.top]);
    return 0;
}

int chckop(char x) {
    if(x=='+') return 1;
    if(x=='-') return 2;
    if(x=='*') return 3;
    if(x=='/') return 4;
    return 0;
}

void reset(Stack *s)
{
    s->top = 0;
}
int isEmpty(Stack *s)
{
    return s->top==0;
}
int isFull(Stack *s)
{
    return s->top==MAXSIZE;
}
void push(Stack *s,TYPE val)
{
    if(!isFull(s)) s->data[(s->top)++] = val;
}
TYPE pop(Stack *s)
{
    return s->data[--(s->top)];
}
void display(Stack s)
{
    while(!isEmpty(&s)) printf("[%d]\n", pop(&s));
}