C确定堆栈溢出

Question

I've made the code above and I've used 2 different compilers, one says "Segmentation Fault" and the other one says "handle_exceptions: Exception: STATUS_STACK_OVERFLOW". Here is the code.

int main() {
    int k, x, f, i, j, tmp, ct;
    scanf("%d %d", &k, &x);
    int w[k];
    for( f = 0; f<k; f++){
        scanf(" %d", &w[f]);
    }
    while(x--){
        scanf("%d %d", &i, &j);
        tmp = 3;
        for(ct = j; i<=ct<=j; ct--){
            if(tmp > w[ct]){
                tmp = w[ct];
            }
        }
        printf("%d\n", tmp);
    }
    return 0;
}

I've commented this code, line by line, and testing and I've the error here:

int w[k];

I don't know what I can do, because the k variable is already defined when the declaration of this vector happens. Can somebody help me?

Answer 1

If you defined an array like this:

int w[k];

It will be stored in the stack, which has a limited size.

If you initialize with malloc the data will be store in the heap (which also has a limited size, but it will allow you to store more data)

int *w = malloc(sizeof(int) * k);

Have you tried this?

Check this for a difference between stack vs heap.

Always checked the returned value from malloc() , this is just an example, but it is a bad practice to not the returned value of malloc() .

Answer 2

You cannot define a variable size during run-time unless you use dynamic memory allocation.

As I can see, you are trying to set the variable size based on the user's input.

To do this, you must use dynamic memory allocation.

scanf("%d %d", &k, &x);
if(k > MAX_SIZE) {
    return -1;
}
int *w = malloc(sizeof(int) * k);

Now you have a memory allocated based on the size entered by user's input. But make sure that you are imposing some limits, because the heap memory is limited.