Why is there an infinite loop in my program?

arrays, c, for-loop, infinite-loop

Solution

Here is what happenning in the given code.

#include<stdio.h>
#include<string.h>
int main(void)
{
    int i;
    int array[5];

    for (i = 0; i <= 20; i++)
    {
        printf("%p %p \n",&i,&array[i]);
        printf("the value of i is %d \n",i);
        sleep(1);
        array[i] = 0;
        printf("i may be modified here lets see what i is %d \n", i);
    }

    return 0;
}

in my stack memory I got the address locations as

`i` is stored at location 0xbfd1048c address

and `array` is stored at location 0xbfd10478 address

As you are incrementing `i` value for each loop at one point of time the address of `array[i]` is equivalent to address of `i` (its just pointer dereferencing)

So what you are storing at `array[i]` is nothing but the `i`'s instance address so you are over writing the `i`'s instance value to 0 as you have mentioned `array[i] = 0` which is equivalent to `i=0` so the condition `i<=20` always succeeds.

Now the BIG question why does the memory allocated in such a way.

It is decided at run time and on the availability of the resources to the kernel.

So that's why we have to dwell with in the limits of the array.

Problem

Original source