Question

What am I missing? If I want to increment a counter in a separate function, why does it give me a segmentation fault?

int point(int *cow);

int main()
{
    int *cow = 0;
    point(cow);
    return(0);

}

int point(int *cow) {
    (*cow)++;
    return(0);
}

Answer 1

Dereferencing a null pointer is undefined behavior in C.

Maybe you wanted to do this instead:

int a = 0;
int *cow = &a;

point(cow);

Note that the temporary pointer cow is not necessary and you can directly pass &a to point function.