argv and polish notation calculator

Question

I'm trying to solve a K&R exercise(5.10) that uses the argc and argv arguments.It's supposed to be a polish notation calculator that uses command line arguments as its' input.Well,the program runs fine for the '+' and '-' operators but I get errors for '*'.I figured out that it has something to do specifically with the '*' symbol,because if I replace it with something else the program works.Any ideas?Thank you.
Note:I didn't include the functions stack_in,stack_out and print_stack.I think they're good.

#include <stdio.h>
#define MAXST 10
#define NUMBER '1'

void stack_in(int n);
int stack_out(void);
void print_stack(void);

int main(int argc,char **argv)
{
  char c,k;

while(--argc>0 && ++argv)
    while(c=*(*argv)++){
        if(c>='0' && c<='9')
            k=NUMBER;
        else
            k=c;
        switch (k){
            int g1,g2;

            case NUMBER:stack_in(c-'0');
                    break;
            case '+':g1=stack_out();
                 g2=stack_out();
                 stack_in(g1+g2);
                 break;
            case '-':g1=stack_out();
                 g2=stack_out();
                 stack_in(g2-g1);
                 break;
            case '*':g1=stack_out();
                 g2=stack_out();
                 stack_in(g1*g2);
                 break;
            default:printf("error on switch \n");
                break;
        }
}

print_stack();

return 0;
}

Answer 1

I think I've done that very exercise!

Anyway, it's likely that the * operator on the command line is turning into "all the files in the directory" which won't work. So you need to quote it when you call the program:

# rpmprog 2 3 '*'

or you can use back-quotes for most shells:

# rpmprog 2 3 \*

Answer 2

On Linux/UNIX shells, you should enclose the * between single quotes '*' if you don't want it to be expanded by your shell.

Answer 3

Your operating system uses "*" for a wildcard on the command line; no changes you make to your program will affect this. You may be able to "escape" the symbol on the command line -- i.e.,

calculator 2 2 \*