Question

I’ve been trying to create a tester for my Stack ADT, by dynamically passing in the amount of items to add to the stack. However, when I try passing in an integer, for instance, 22, it assigns the global variable (ITEMS) as 50. If I try something else, the range is between 45, and 55.

My main function is this:

int main(int numArgs, char* numItems[]) {
    Stack stack;

    if (numArgs == 0) {
        printf("Good job, you broke C.\n");
    } else if (numArgs == 2) {
        int items = (int)*numItems[1];
        if(*numItems[1] != ITEMS) {
            setItems(items);
        } 
    } else if (numArgs>=3) {
        printf("Usage: TestStack <numItems> <-help>\n");
        exit(1);
    } else if(numItems[1] == "-h" || numItems[2] == "-help") {
        printf("numItems   - Number of items to add to the stack.\n            -h     (-help) -  Shows this help output.\n");
        exit(1);
    }
    /* test code here*/
}

The assignment function is:

static void setItems(int numItems) {
    ITEMS = numItems;
    printf("ITEMS IS %d\n",ITEMS);
}

And my global variable is just

int ITEMS = 11; //Default value.

Any reason that I can’t actually get the real value I’m trying to pass in?

Answer 1

Your problem is here:

int items = (int)*numItems[1];

This will read the int value of the first char that you pass in… Since you pass in 22, it will get the ASCII Valule of 2 which is 50. Refer to this chart (thanks asciitable.com) under Dec 50:

What you want to do instead is interpret the whole cstring as an integer, using atoi:

int items = atoi(numItems[1]);

or strtol:

int items = strtol(numItems[1], NULL, 10);