How to fix strcpy so that it detects overlapping strings

Question

In an interview, I was asked to write an implementation of strcpy and then fix it so that it properly handles overlapping strings. My implementation is below and it is very naiv

Answer 1

I was asked this in a recent interview. We don't have to 'detect' overlap. We can write strcpy in such a way that overlapping addresses are taken care of. The key is to copy from the end of source string instead of from the start.

Here is a quick code.

void str_copy(const char *src, char *dst) 
{
    /* error checks */

    int i = strlen(a); /* may have to account for null character */

    while(i >= 0) 
    {
        dst[i] = src[i];  
        i--; 
    }
}

EDIT: This only works when a < b. For a > b, copy from the start.