This works when I input the values using the keyboard, but I want to have the array declared and the whole string passed on from main() to getop() and still have the same result. I feel the getchar() in the getop() is the problem. Any suggestions how I can do this?
Code:
#include <stdio.h>
#include <stdlib.h> 
#include <ctype.h>
#include <string.h> 
#define MAX 50
#define MAXOP 100 /* max size of operand or operator */
#define NUMBER '0' /* signal that a number was found */
#define MAXVAL 100 /* maximum depth of val stack */

 int getop(char []);
void push(double);
double pop(void);

main()
      {
    int type;
    double op2;
    double a, b,q;
    char array[MAXOP];
    char array[]= "2 4 +"; 

     while ((type = getop(array)) != EOF) {
    switch (type) {
    case NUMBER: push(atof(array));
        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("error: zero divisor\n");
       break;
    case '\n': printf("\t%.8g\n", pop());
    getchar();
    
       break;
    default: printf("error: unknown command %s\n", array);
            break;
    }
  }

return 0;
}
int sp=0;
double val[MAXVAL];
void push(double f)
     {
     if (sp < MAXVAL)
      val[sp++] = f;
     else
     printf("error: stack full, canít push %g\n", f);
     }
double pop(void)
       {
       if (sp > 0)
       return val[--sp];
       else {
             printf("error: stack empty\n");
       return 0.0;
             }
        }
  int getop(char s[]){
         
      int i,c;
     while ((s[0]=c=getchar()) == ' ' || c == '\t'); 
     s[1] = '\0';
     if (!isdigit (c) && c != '.')
     return c; 
     i = 0;
      if (isdigit(c)) 
     while (isdigit(s[++i]=c=getchar()));
     if ( c == '.') 
     while (isdigit(s[++i]=c=getchar()));
     s[i] = '\0';
             
     if ( c != EOF)
     ungetch(c);
     return NUMBER;
}