Reverse Polish Notation Calculator

#include <stdio.h>
#include <math.h>
#define MAXOP 100
#define NUMBER '0'

int getop(char[]);
void push(double);
double pop(void);
/* RPN reverse polish notation calculator*/
//pseudo code, not done yet

main(){
    int type;
    double op2;
    char s[MAXOP];
    while((type=getop(s))!=EOF){
        switch(type){
            case NUMBER:
                push(atof(s));
                break;
            case '+':
                push(pop()+pop());
                break;
            case '*':
                push(pop()*pop());
                break;
            case '-':
                op2=pop();
                push(pop()-op2);
                break;
            case '/':
                op2-pop();
                if(op2!=0.0)
                    push(pop()/op2);
                else
                    printf("greska, deljenje nulom\n");
                break;
            case '\n':
                printf("|t%.8g\n", pop());
                break();
            default:
                printf("greska, nepoznata operacija %s\n", s);
            break;
        }
    }
return 0;
}