Question

Why this stackover flow is happening where as I am using fflush and free in my code.
Please help me.

using namespace std;

    struct abc{
        int x;int y;
        }abc;

int _tmain(int argc, _TCHAR* argv[])
{
    struct abc *xyz = (struct abc *) malloc(sizeof(struct abc));
    xyz->x = 5;
    printf("%d\n", xyz->x);
    //system("pause");
        free(xyz);
     // xyz = NULL;
        fflush(stdout);
        _tmain(NULL, NULL);

    return 0;
}

Edited Code:

xyz:
    struct abc *xyz = (struct abc *) malloc(sizeof(struct abc));
    xyz->x = 5;
    printf("%d\n", xyz->x);
    //system("pause");

    free(xyz);
    xyz = NULL;
    fflush(stdout);
    goto xyz;

Answer 1

You are unconditonally calling the _tmain() function from your _tmain() function, causing infinite recursion. Every call needs to allocate space on the stack (which is never freed), causing your StackOverflow exception. Take a look at e.g. Wikipedia too fully understand the problem.

Apart from that, calling the main() function from your own code is ususally not a good idea, as its forbidden by the standard.

§3.6.1.3: The function main shall not be used within a program.

Why would you need to do that?