very unexpected values from *argv[]

[GiForce]

Hi
Some code here, pushing values on a stack untill it finds an operator, and then does (it should) the operation. The first part pushing the values is working fine. Then, when it doesn't find a digit anymore and executes the switch arguments, it does something, for me, strange. When I output the values it recieves, instead operators (in ascii) it recieves letters, starting with several 'A's. I'm pretty sure to handle the casting/pointer for the switch input wrong, but nevertheless I can't explain the values, where they came from and why that many?
--> given the input: exp 2 3 *

int main(int argc, char *argv[])
{
    int n;
    double op2;
    while (--argc > 0) {
        if (isdigit(n = **++argv)) 
            push(atof(*argv));  // 
        else {
            switch (n) {
                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;

[Salem]

> if (isdigit(n = **++argv))
> push(atof(*argv)); //
Try writing it out in long form, instead of a super-compressed embedded assignment and pointer arithmetic.

IE, spend a few seconds more writing clear code, instead of spending days wondering why your "clever" code has out-smarted you.

[algorism]

Remember that if you're passing characters special to the shell you need to escape them:
$ calc 2 3 \*
Otherwise you'll get a list of filenames instead (on linux at least)!

[GiForce]

Thank you 4 your responses!
@Salem, that code never meant to be 'clever', I'm following the book "Programmieren in C" ("The C Programming Language") and use the techniques given at the time. But I understand what you mean, I will remember this to practise when I run into confusion, promise
But have to admit, I really love that part of C (especially compared to python, which has also it's beauty) how you can embed assignments and incremention in conditions, it's beautiful
@algorism You are right, thats the point!
Used the same conditions earlier in the book I'm reading, where we grabbed the characters with getchar(), maybe I can use this again somehow. I'll see!
HAve a beautiful day all!

[GiForce]

There seems no way around when using bash-command-line. But, well, that's okay, I see clear here now. Thank you very much, again! Yu are the best.
--> I can't mark that thread as closed, can I ?